Character data string match determination by loading registers at most up to memory block boundary and comparing to avoid unwarranted exception

ABSTRACT

Multiple sets of character data having termination characters are compared using parallel processing and without causing unwarranted exceptions. Each set of character data to be compared is loaded within one or more vector registers. In particular, in one embodiment, for each set of character data to be compared, an instruction is used that loads data in a vector register to a specified boundary, and provides a way to determine the number of characters loaded. Further, an instruction is used to find the index of the first delimiter character, i.e., the first zero or null character, or the index of unequal characters. Using these instructions, a location of the end of one of the sets of data or a location of an unequal character is efficiently provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/421,614, filed Mar. 15, 2012, entitled “COMPARING SETS OFCHARACTER DATA HAVING TERMINATION CHARACTERS,” which is herebyincorporated herein by reference in its entirety.

BACKGROUND

An aspect of the invention relates, in general, to text processing, andin particular, to processing associated with character data.

Text processing often requires various types of character dataprocessing, including the processing of character data strings. Sometypes of processing include finding the termination point (e.g., end ofa string), determining the length of the character data, finding aparticular character, comparing characters, etc. Current instructionsand/or techniques to perform these types of processing tend to beinefficient.

BRIEF SUMMARY

The shortcomings of the prior art are overcome and advantages areprovided through the provision of a method of comparing characters of aplurality of sets of data. The method includes, for instance, loadingfrom memory to a first register, a variable amount of first data that iswithin a first specified block of memory, the first data being at leasta portion of a first set of data to be compared, and the loadingcomprising loading the first data into the first register withoutcrossing a first specified boundary of the memory from which the data isloaded, wherein the loading starts at a first starting address andterminates at a first ending address, the first ending addressdetermined such that the first specified boundary is not crossed;loading from memory to a second register, second data that is within asecond specified block of memory, the second data being at least aportion of a second set of data to be compared; computing a first countof an amount of first data loaded in the first register and a secondcount of an amount of the second data loaded in the second register;determining, by a processor, a value, the determining includingperforming at least one of A) or B): A) comparing the first data loadedin the first register with the second data loaded in the second registersearching for an unequal character; and B) searching at least one of thefirst register and the second register for a termination character; andbased on at least one of the comparing and the searching, setting thevalue to one of a location of the unequal character, a location of thetermination character, or a pre-specified value based on not finding anunequal character or a termination character; checking whether the firstset of data or the second set of data has additional data to becompared, the checking using at least one of the first count and thesecond count; and based on the checking indicating additional data is tobe compared, comparing the additional data of the first set of data orthe second set of data with data of the other set of the first set ofdata or the second set of data.

Computer program products and systems relating to one or more aspects ofthe present invention are also described and may be claimed herein.Further, services relating to one or more aspects of the presentinvention are also described and may be claimed herein.

Additional features and advantages are realized through the techniquesof the present invention. Other embodiments and aspects of the inventionare described in detail herein and are considered a part of the claimedinvention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One or more aspects of the present invention are particularly pointedout and distinctly claimed as examples in the claims at the conclusionof the specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 depicts one example of a computing environment to incorporate anduse one or more aspects of the present invention;

FIG. 2A depicts another example of a computing environment toincorporate and use one or more aspects of the present invention;

FIG. 2B depicts further details of the memory of FIG. 2A, in accordancewith an aspect of the present invention;

FIG. 3 depicts one embodiment of the logic to compare sets of terminatedcharacter data, in accordance with an aspect of the present invention;

FIGS. 4A and 4B depict examples of main memory from which data is loadedinto vector registers, in accordance with an aspect of the presentinvention;

FIGS. 4C and 4E depict examples of vector registers loaded withcharacter data from the main memory of FIG. 4A, in accordance with anaspect of the present invention;

FIGS. 4D and 4F depict examples of vector registers loaded withcharacter data from the main memory of FIG. 4B, in accordance with anaspect of the present invention;

FIG. 5 depicts one embodiment of a format of a Vector Load to BlockBoundary instruction, in accordance with an aspect of the presentinvention;

FIG. 6A depicts one embodiment of the logic associated with the VectorLoad to Block Boundary instruction, in accordance with an aspect of thepresent invention;

FIG. 6B depicts another embodiment of the logic associated with theVector Load to Block Boundary instruction, in accordance with an aspectof the present invention;

FIG. 7 depicts one embodiment of a format of a Vector Find Element NotEqual instruction, in accordance with an aspect of the presentinvention;

FIG. 8 depicts one embodiment of the logic associated with a Vector FindElement Not Equal instruction, in accordance with an aspect of thepresent invention;

FIG. 9 depicts one embodiment of various processing blocks to performthe logic of FIG. 8, in accordance with an aspect of the presentinvention;

FIG. 10 depicts one embodiment of a format of a Load Count to BlockBoundary instruction, in accordance with an aspect of the presentinvention;

FIG. 11 depicts one embodiment of the logic associated with a Load Countto Block Boundary instruction, in accordance with an aspect of thepresent invention;

FIG. 12 depicts one example of a register file, in accordance with anaspect of the present invention;

FIG. 13 depicts one embodiment of a computer program productincorporating one or more aspects of the present invention;

FIG. 14 depicts one embodiment of a host computer system to incorporateand use one or more aspects of the present invention;

FIG. 15 depicts a further example of a computer system to incorporateand use one or more aspects of the present invention;

FIG. 16 depicts another example of a computer system comprising acomputer network to incorporate and use one or more aspects of thepresent invention;

FIG. 17 depicts one embodiment of various elements of a computer systemto incorporate and use one or more aspects of the present invention;

FIG. 18A depicts one embodiment of the execution unit of the computersystem of FIG. 17 to incorporate and use one or more aspects of thepresent invention;

FIG. 18B depicts one embodiment of the branch unit of the computersystem of FIG. 17 to incorporate and use one or more aspects of thepresent invention;

FIG. 18C depicts one embodiment of the load/store unit of the computersystem of FIG. 17 to incorporate and use one or more aspects of thepresent invention; and

FIG. 19 depicts one embodiment of an emulated host computer system toincorporate and use one or more aspects of the present invention.

DETAILED DESCRIPTION

In accordance with an aspect of the present invention, a capability isprovided for facilitating processing of character data, including, butnot limited to, alphabetic characters, in any language; numeric digits;punctuation; and/or other symbols. The character data may or may not bestrings of data. Associated with character data are standards, examplesof which include, but are not limited to, ASCII (American Standard Codefor Information Interchange); Unicode, including, but not limited to,UTF (Unicode Transformation Format) 8; UTF16; etc.

In one aspect, a technique is provided for comparing multiple sets ofcharacter data that have termination characters (e.g., null terminatedstrings of characters) using parallel processing and without causingunwarranted exceptions. Each set of character data (also referred toherein as character data or terminated character data) to be compared isloaded, for instance, within one or more vector registers. Inparticular, in one embodiment, for each set of character data to becompared, an instruction (e.g., a Vector Load to Block Boundaryinstruction) is used that loads data in parallel in a vector register toa specified boundary (such as a cache or page boundary), and provides away to determine the number of characters loaded. In one embodiment, todetermine the number of characters loaded (a count) for each set ofcharacter data, another instruction (e.g., a Load Count to BlockBoundary instruction) is used. Further, an instruction (e.g., a VectorFind Element Not Equal instruction) is used to search the loaded datafor the first delimiter character within the set of character data,e.g., the first termination character, such as a zero or null character;or the first unequal character (e.g., a character in one position of oneset of data is different from a character in the same position inanother set of data). This instruction checks a plurality of bytes ofdata in parallel. By using these instructions, multiple sets ofterminated character data may be compared using only one branchinstruction. Further, fast parallel checking of the character data isprovided, while preventing spurious exceptions.

As described herein, an element of a vector register (a.k.a., a vector)is one, two or four bytes in length, as examples; and a vector operandis, for instance, a SIMD (Single Instruction, Multiple Data) operandhaving a plurality of elements. In other embodiments, elements can be ofother sizes; and a vector operand need not be SIMD, and/or may includeone element.

One embodiment of a computing environment to incorporate and use one ormore aspects of the present invention is described with reference toFIG. 1. A computing environment 100 includes, for instance, a processor102 (e.g., a central processing unit), a memory 104 (e.g., main memory),and one or more input/output (I/O) devices and/or interfaces 106 coupledto one another via, for example, one or more buses 108 and/or otherconnections.

In one example, processor 102 is based on the z/Architecture offered byInternational Business Machines Corporation, and is part of a server,such as the System z server, which is also offered by InternationalBusiness Machines Corporation, and implements the z/Architecture. Oneembodiment of the z/Architecture is described in an IBM® publicationentitled, “z/Architecture Principles of Operation,” IBM® Publication No.SA22-7832-08, Ninth Edition, August, 2010, which is hereby incorporatedherein by reference in its entirety. In one example, the processorexecutes an operating system, such as z/OS, also offered byInternational Business Machines Corporation. IBM®, Z/ARCHITECTURE® andZ/OS® are registered trademarks of International Business MachinesCorporation, Armonk, N.Y., USA. Other names used herein may beregistered trademarks, trademarks, or product names of InternationalBusiness Machines Corporation or other companies.

In a further embodiment, processor 102 is based on the PowerArchitecture offered by International Business Machines Corporation. Oneembodiment of the Power Architecture is described in “Power ISA™ Version2.06 Revision B,” International Business Machines Corporation, Jul. 23,2010, which is hereby incorporated herein by reference in its entirety.POWER ARCHITECTURE® is a registered trademark of International BusinessMachines Corporation.

In yet a further embodiment, processor 102 is based on an Intelarchitecture offered by Intel Corporation. One embodiment of the Intelarchitecture is described in “Intel® 64 and IA-32 ArchitecturesDeveloper's Manual: Vol. 2B, Instructions Set Reference, A-L,” OrderNumber 253666-041US, December 2011, and “Intel® 64 and IA-32Architectures Developer's Manual: Vol. 2B, Instructions Set Reference,M-Z,” Order Number 253667-041US, December 2011, each of which is herebyincorporated herein by reference in its entirety. Intel® is a registeredtrademark of Intel Corporation, Santa Clara, Calif.

Another embodiment of a computing environment to incorporate and use oneor more aspects of the present invention is described with reference toFIG. 2A. In this example, a computing environment 200 includes, forinstance, a native central processing unit 202, a memory 204, and one ormore input/output devices and/or interfaces 206 coupled to one anothervia, for example, one or more buses 208 and/or other connections. Asexamples, computing environment 200 may include a PowerPC processor, apSeries server or an xSeries server offered by International BusinessMachines Corporation, Armonk, N.Y.; an HP Superdome with Intel ItaniumII processors offered by Hewlett Packard Co., Palo Alto, Calif.; and/orother machines based on architectures offered by International BusinessMachines Corporation, Hewlett Packard, Intel, Oracle, or others.

Native central processing unit 202 includes one or more native registers210, such as one or more general purpose registers and/or one or morespecial purpose registers used during processing within the environment.These registers include information that represents the state of theenvironment at any particular point in time.

Moreover, native central processing unit 202 executes instructions andcode that are stored in memory 204. In one particular example, thecentral processing unit executes emulator code 212 stored in memory 204.This code enables the processing environment configured in onearchitecture to emulate another architecture. For instance, emulatorcode 212 allows machines based on architectures other than thez/Architecture, such as PowerPC processors, pSeries servers, xSeriesservers, HP Superdome servers or others, to emulate the z/Architectureand to execute software and instructions developed based on thez/Architecture.

Further details relating to emulator code 212 are described withreference to FIG. 2B. Guest instructions 250 comprise softwareinstructions (e.g., machine instructions) that were developed to beexecuted in an architecture other than that of native CPU 202. Forexample, guest instructions 250 may have been designed to execute on az/Architecture processor 102, but instead, are being emulated on nativeCPU 202, which may be, for example, an Intel Itanium II processor. Inone example, emulator code 212 includes an instruction fetching unit 252to obtain one or more guest instructions 250 from memory 204, and tooptionally provide local buffering for the instructions obtained. Italso includes an instruction translation routine 254 to determine thetype of guest instruction that has been obtained and to translate theguest instruction into one or more corresponding native instructions256. This translation includes, for instance, identifying the functionto be performed by the guest instruction and choosing the nativeinstruction(s) to perform that function.

Further, emulator 212 includes an emulation control routine 260 to causethe native instructions to be executed. Emulation control routine 260may cause native CPU 202 to execute a routine of native instructionsthat emulate one or more previously obtained guest instructions and, atthe conclusion of such execution, return control to the instructionfetch routine to emulate the obtaining of the next guest instruction ora group of guest instructions. Execution of the native instructions 256may include loading data into a register from memory 204; storing databack to memory from a register; or performing some type of arithmetic orlogic operation, as determined by the translation routine.

Each routine is, for instance, implemented in software, which is storedin memory and executed by native central processing unit 202. In otherexamples, one or more of the routines or operations are implemented infirmware, hardware, software or some combination thereof. The registersof the emulated processor may be emulated using registers 210 of thenative CPU or by using locations in memory 204. In embodiments, guestinstructions 250, native instructions 256 and emulator code 212 mayreside in the same memory or may be disbursed among different memorydevices.

As used herein, firmware includes, e.g., the microcode, millicode and/ormacrocode of the processor. It includes, for instance, thehardware-level instructions and/or data structures used inimplementation of higher level machine code. In one embodiment, itincludes, for instance, proprietary code that is typically delivered asmicrocode that includes trusted software or microcode specific to theunderlying hardware and controls operating system access to the systemhardware.

In one example, a guest instruction 250 that is obtained, translated andexecuted is one or more of the instructions described herein. Theinstruction, which is of one architecture (e.g., the z/Architecture) isfetched from memory, translated and represented as a sequence of nativeinstructions 256 of another architecture (e.g., PowerPC, pSeries,xSeries, Intel, etc.). These native instructions are then executed.

In one embodiment, various instructions described herein are vectorinstructions, which are part of a vector facility, provided inaccordance with an aspect of the present invention. The vector facilityprovides, for instance, fixed sized vectors ranging from one to sixteenelements. Each vector includes data which is operated on by vectorinstructions defined in the facility. In one embodiment, if a vector ismade up of multiple elements, then each element is processed in parallelwith the other elements. Instruction completion does not occur untilprocessing of all the elements is complete.

As described herein, vector instructions can be implemented as part ofvarious architectures, including, but not limited to, thez/Architecture, Power, Intel, etc. Although an embodiment describedherein is for the z/Architecture, the vector instructions and one ormore aspects of the present invention may be based on many otherarchitectures. The z/Architecture is only one example.

In one embodiment in which the vector facility is implemented as part ofthe z/Architecture, to use the vector registers and instructions, avector enablement control and a register control in a specified controlregister (e.g., control register 0) are set to, for instance, one. Ifthe vector facility is installed and a vector instruction is executedwithout the enablement controls set, a data exception is recognized. Ifthe vector facility is not installed and a vector instruction isexecuted, an operation exception is recognized.

Vector data appears in storage, for instance, in the same left-to-rightsequence as other data formats. Bits of a data format that are numbered0-7 constitute the byte in the leftmost (lowest-numbered) byte locationin storage, bits 8-15 form the byte in the next sequential location, andso on. In a further example, the vector data may appear in storage inanother sequence, such as right-to-left.

Many of the vector instructions provided with the vector facility have afield of specified bits. This field, referred to as the registerextension bit or RXB, includes the most significant bit for each of thevector register designated operands. Bits for register designations notspecified by the instruction are to be reserved and set to zero.

In one example, the RXB field includes four bits (e.g., bits 0-3), andthe bits are defined, as follows:

-   -   0—Most significant bit for the first vector register designation        of the instruction.    -   1—Most significant bit for the second vector register        designation of the instruction, if any.    -   2—Most significant bit for the third vector register designation        of the instruction, if any.    -   3—Most significant bit for the fourth vector register        designation of the instruction, if any.

Each bit is set to zero or one by, for instance, the assembler dependingon the register number. For instance, for registers 0-15, the bit is setto 0; for registers 16-31, the bit is set to 1, etc.

In one embodiment, each RXB bit is an extension bit for a particularlocation in an instruction that includes one or more vector registers.For instance, in one or more vector instructions, bit 0 of RXB is anextension bit for location 8-11, which is assigned to e.g., V₁; bit 1 ofRXB is an extension bit for location 12-15, which is assigned to, e.g.,V₂; and so forth.

In a further embodiment, the RXB field includes additional bits, andmore than one bit is used as an extension for each vector or location.

As described herein, various instructions are used, in accordance withan aspect of the present invention, in order to compare sets ofcharacter data that have termination characters using parallelprocessing. Processing associated with the comparing and the variousinstructions used are described in further detail below. In theembodiment described herein, characters of two null terminated stringsare compared; however, in other embodiments, more than two strings orother character data sets may be compared. Also, character data setsother than null terminated strings may also be compared.

Referring initially to FIG. 3, in one embodiment, to compare charactersof two sets of terminated character data, such as two null terminatedcharacter strings, each of two vector registers is loaded with characterdata using, for instance, the Vector Load to Block Boundary instruction,STEPs 300 a, 300 b. Each instruction loads up to, for instance, 16 bytesof data in parallel without crossing a specified boundary of the mainmemory from which the data is loaded. Details relating to thisinstruction are described below. In this embodiment, the two loadinstructions are performed in parallel.

Thereafter, the number of loaded bytes of data is determined for eachloaded vector using, for instance, a Load Count to Block Boundaryinstruction, described below, STEPs 302 a, 302 b. Again, in oneembodiment, these instructions are performed in parallel.

Next, a search for the end of the character data (e.g., for null orzero) or for character inequality is performed, STEP 304. In oneexample, a Vector Find Element Not Equal instruction, described below,is used to search for the terminating character (i.e., for null, zero oranother termination character) or the unequal character. Thisinstruction compares data of the two vectors for inequality and searchesa selected vector register for null elements, also referred to as zeroelements (e.g., entire element is zero). A null or zero elementindicates termination of the character data; e.g., an end of aparticular string of data. A result of the search of the loaded vectorsis an index (e.g., a byte index) of the first non-equal element or thefirst null element, referred to herein as the termination character, ora pre-specified value, such as the size of the vectors being compared,if no termination character or unequal element is found.

Thereafter, the minimum between the counts for the two vectors iscomputed, STEP 306. For instance, the minimum is determined by Min(lenA, len B), where len A is the count for the vector register loaded at300 a, and len B is the count for the vector register loaded at 300 b.

Next, the index determined by the Vector Find Element Not Equalinstruction in incremented by the minimum computed in STEP 306, STEP308. Thereafter, a determination is made as to whether the minimum(e.g., determined in STEP 306) is less than the search index (e.g.,determined from the Vector Find Element Not Equal instruction), INQUIRY310. If the minimum is less than the index, then processing continueswith STEP 300. Otherwise, processing associated with comparing the setsof character data is complete.

At conclusion of the logic for comparing multiple sets of terminatedcharacter data, a result is available that indicates a location (e.g.,byte index) of a first unequal character found or a location of a firsttermination character. Example pseudo-code used to compare terminatedcharacter data, such as null terminated strings, is provided below:

RB1-STR1@, RB2-STR2@, R3-Return value XGR RX, RX, RX Initialize Rx to 0LOOP VLBB VST1, 0 (RX, RB1), 4K Load str1 into VST1 VLBB VST2, 0 (Rx,RB2), 4K Load str2 into VST2 VFBNEZ VPOS, VST1, VST2 Compare loadedstrings VLGVB GPOS, VPOS, 7(0) Extract index to gpr (16-no match) LCBBGLN1, 0 (RX, RB1), 4K Get load byte count for RB1 LCBB GLN2, 0 (RX,RB2), 4K Get load byte count for RB2 CGR GLN1, GLN2 Compare countsLOCGRGT GLN1, GLN2 Determine minimum count AGR RX, RX GLN1 Inc smallestload amt CGR GLN1, GPOS See if miscompare in portion loaded BRLE LOOP *SGR RX, RX, GLN1 Subtract AGR RX, RX, GPOS Add LB R3, 0 (RX, RB1) Loadbyte LB R5, 0 (RX, RB2) SGR R3, R3, R5 Subtract

As shown above, initially a register, RX, is initialized to zero, byperforming, for instance, an XOR between RX and RX and placing theresult in RX. Then, a loop begins, in which up to 16 bytes of data areloaded in each of two vectors, VST1 and VST2. A compare of the loadeddata is performed for inequality and a search for a null element in oneof the vectors is performed. Based on the compare and search, a value isplaced in VPOS. The index is then extracted from VPOS and placed in ageneral purpose register (GPOS). Counts of the number of bytes loaded inVST1 and VST2 are determined and placed in variables, GLN1 and GLN2.Thereafter, GLN1 and GLN2 are compared to determine the smallest, and RXis incremented by the smallest load amount. A determination is made tosee if a miscompare or null element is in the loaded portion. If not,loop. Otherwise, some cleanup is performed, as indicated above at SGR,AGR, LB, LB and SGR.

One example of main memory 400 from which a vector register is loadedand compared is depicted in FIG. 4A. As shown, this portion of mainmemory includes the character data “Hello World!” A boundary of the mainmemory that is not to be crossed in loading the data is shown by thevertical dashed line 402. The main memory data is loaded into vectorregisters 420, 440, examples of which are depicted in FIGS. 4C and 4E.That is, up to the boundary is loaded in vector register 420 (FIG. 4C),and the remainder is loaded in vector register 440 (FIG. 4E), as shownin the below pseudo-code.

Further, main memory 410 from which a vector register is loaded andcompared is depicted in FIG. 4B. As shown, this portion of memory alsoincludes the character data “Hello World!” but the boundary of thememory that is not to be crossed in loading the data is at a differentlocation shown by the vertical dashed line 412. This data is loaded intovector registers 430 and 450, examples of which are depicted in FIGS. 4Dand 4F.

In the example of FIG. 4B, although the entire set of character data isable to be loaded in a vector register (See e.g., FIG. 4D) withoutcrossing a memory boundary, data is still re-loaded in vector 450 (FIG.4F), since this data is to be compared to the loaded data in vector 440(FIG. 4E). The starting address of the data loaded in vector 450 is atthe same position in the character data set as the starting address forvector 440.

One example of pseudo-code to load data from the memory (referred to inthe pseudo-code as STR1, STR2) is provided below:

VLBB V1, 0(RX, STR1), 4K See FIG. 4C VLBB V2, 0(RX, STR2), 4K See FIG.4D VFBNEZ V3, V1, V2 VLGVB G3, V3, 7(0) G3 = 9 LCBB G1, 0(RX, STR1), 4KG1 = 9 LCBB G2, 0(RX, STR2), 4K G2 = 16 CGR G1, G2 LOCGR G1, G2 AGR RX,RX, G1 RX = 9 CGR G1, G3 BRLE LOOP → TAKEN VLBB V1, 0(RX, STR1), 4K SeeFIG. 4E - load starting at RX, RX = 9 VLBB V2, 0(RX, STR2), 4K See FIG.4F - load starting at RX, RX = 9 VFBNEZ V3, V1, V2 VLGVB G3, V3, 7(0) G3= 3 LCBB G1, 0(RX, STR1), 4K G1 = 16 LCBB G2, 0(RX, STR2), 4K G2 = 16 .. . BRLE LOOP → Not Taken . . .

As indicated above, in one embodiment, in order to compare sets ofterminated character data, such as null terminated character strings,various instructions are used. Examples of these instructions aredescribed in detail below.

One instruction used to load the vector register is a Vector Load toBlock Boundary (VLBB) instruction, an example of which is described withreference to FIG. 5. In one example, the Vector Load To Block Boundaryinstruction 500 includes opcode fields 502 a (e.g., bits 0-7), 502 b(e.g., bits 40-47) indicating a Vector Load To Block Boundary operation;a vector register field 504 (e.g., bits 8-11) used to designate a vectorregister (V₁); an index field (X₂) 506 (e.g., bits 12-15); a base field(B₂) 508 (e.g., bits 16-19); a displacement field (D₂) 510 (e.g., bits20-31); a mask field (M₃) 512 (e.g., bits 32-35); and an RXB field 514(e.g., bits 36-39). Each of the fields 504-514, in one example, isseparate and independent from the opcode field(s). Further, in oneembodiment, they are separate and independent from one another; however,in other embodiments, more than one field may be combined. Furtherinformation on the use of these fields is described below.

In one example, selected bits (e.g., the first two bits) of the opcodedesignated by opcode field 502 a specify the length and format of theinstruction. In this particular example, the length is three halfwords,and the format is a vector register-and-index-storage operation with anextended opcode field. The vector (V) field, along with itscorresponding extension bit specified by RXB, designates a vectorregister. In particular, for vector registers, the register containingthe operand is specified using, for instance, a four-bit field of theregister field with the addition of the register extension bit (RXB) asthe most significant bit. For instance, if the four bit field is 0110and the extension bit is 0, then the five bit field 00110 indicatesregister number 6.

The subscript number associated with a field of the instruction denotesthe operand to which the field applies. For instance, the subscriptnumber 1 associated with V₁ denotes the first operand, and so forth. Theregister operand is one register in length, which is, for instance, 128bits.

In one example, in a vector register-and-index storage operationinstruction, the contents of general registers designated by the X₂ andB₂ fields are added to the contents of the D₂ field to form the secondoperand address. The displacement, D₂, for the Vector Load To BlockBoundary instruction is treated as a 12 bit unsigned integer, in oneexample.

The M₃ field, in one embodiment, specifies a code that is used to signalthe CPU as to the block boundary to load to. If a reserved value isspecified, a specification exception is recognized. Example codes andcorresponding values are as follows:

Code Boundary 0 64-Byte 1 128-Byte 2 256-Byte 3 512-Byte 4 1K-Byte 52K-Byte 6 4K-Byte

In execution of one embodiment of the Vector Load To Block Boundaryinstruction, preceding in one embodiment from left to right, the firstoperand (specified in the register designated by the V₁ field plus theextension bit) is loaded starting at the zero indexed byte element withbytes from the second operand. The second operand is a memory locationdesignated by the second operand address (also referred to as a startingaddress). The loading starts from that memory location and continues toan ending address computed by the instruction (or processor), asdescribed below. If a boundary condition is encountered, it ismodel-dependent on how the rest of the first operand is treated. Accessexceptions are not recognized on bytes not loaded. In one example, bytesthat are not loaded are unpredictable.

In the example instruction above, the starting address is determined bythe index register value (X₂)+a base register value (B₂)+a displacement(D₂); however, in other embodiments, it is provided by a register value;an instruction address+instruction text specified offset; a registervalue+displacement; or a register value+index register value; as justsome examples. Further, in one embodiment, the instruction does notinclude the RXB field. Instead, no extension is used or the extension isprovided in another manner, such as from a control outside of theinstruction, or provided as part of another field of the instruction.

Further details of one embodiment of processing associated with theVector Load to Block Boundary instruction are described with referenceto FIG. 6A. In this example, a boundary size is specified in theinstruction. In one example, a processor of the computing environment isperforming this logic.

In one embodiment, initially a boundary mask (BdyMask) is created, whichis used to determine closeness to the specified boundary, STEP 600. Tocreate the mask, in one example, a 2's complement negation of a boundarysize (BdySize) 602 is taken creating boundary mask 604 (e.g.,BdyMask=0−BdySize). The boundary size is provided, in one example, bythe instruction (e.g., the M₃ field); or in another example, it isdetermined by the machine, as described herein.

Thereafter, a start address is computed, which indicates a location inmemory from which loading is to begin, STEP 610. As examples, the startaddress 612 can be provided by a register value; an instruction addressplus instruction text specified offset; a register value plusdisplacement; a register value plus index register value; or a registervalue plus index register value plus displacement. In the instructionprovided herein, the start address is provided by the X₂ field, B₂ fieldand D₂ field. That is, contents of the registers designated by X₂ and B₂are added to the displacement indicated by D₂ to provide the startingaddress. The above-indicated ways to compute a starting address are justexamples; other examples are also possible.

Next, an end address is computed indicating where to stop loading from,STEP 620. Input to this computation is, for instance, boundary size 602,start address 612, vector size 614 (e.g., in bytes; e.g., 16), andboundary mask 604. In one example, end address 622 is computed asfollows:EndAddress=min(StartAddress+(BdySize−(StartAddress &−BdyMask)),StartAddress+vec_size).

Thereafter, the first operand (i.e., the designated vector register) isloaded, starting at indexed byte 0, from memory commencing at thestarting address and terminating at the ending address, STEP 630. Thisenables a variable number of bytes to be loaded from memory into avector without crossing a designated memory boundary. For instance, ifthe memory boundary is at 64 bytes, and the starting address is at 58bytes, then bytes 58-64 are loaded in the vector register. In oneembodiment, the bytes are loaded in parallel.

Another embodiment of processing associated with the Vector Load toBlock Boundary instruction is described with reference to FIG. 6B. Inthis embodiment, the boundary size is not specified by the instruction,but instead, the boundary size is dynamically determined by theprocessor executing the instruction.

In one embodiment, initially, a start address is computed, whichindicates a location in memory from which loading is to begin, STEP 650.As examples, the start address 652 can be provided by a register value;an instruction address plus instruction text specified offset; aregister value plus displacement; a register value plus index registervalue; or a register value plus index register value plus displacement.In the instruction provided herein, the start address is provided by theX₂ field, B₂ field and D₂ field. That is, contents of the registersdesignated by X₂ and B₂ are added to the displacement indicated by D₂ toprovide the starting address. The above-indicated ways to compute astarting address are just examples; other examples are also possible.

Thereafter, a determination is made as to whether the boundary is to bedynamically determined, INQUIRY 654. If not, then the value specified inthe M₃ field is used as the boundary size (BdySize). Otherwise, theprocessor dynamically determines the boundary size, STEP 656. Forinstance, the M₃ field specifies the type of boundary (e.g., cache line,page, etc.), and based on the type and one or more characteristics ofthe processor (e.g., cache line size for the processor; page size forthe processor; etc.), the processor determines the boundary. Asexamples, based on the type, the processor uses a fixed size for theboundary (e.g., pre-defined fixed cache line or page size for theprocessor), or based on the type, the processor determines the boundary.For instance, if the type is a page boundary, the processor looks up thestart address in a Translation Look-aside Buffer (TLB) and determinesthe page boundary therefrom. Other examples also exist.

Subsequent to determining the boundary size, either dynamically or byinstruction specified, a boundary mask (BdyMask) is created, which isused to determine closeness to the specified boundary, STEP 660. Tocreate the mask, in one example, a 2's complement negation of a boundarysize (BdySize) 658 is taken creating boundary mask 662 (e.g.,BdyMask=0−BdySize).

Next, an end address is computed indicating where to stop loading from,STEP 670. Input to this computation is, for instance, boundary size 658,start address 652, vector size 664 (e.g., in bytes; e.g., 16), andboundary mask 662. In one example, end address 672 is computed asfollows:EndAddress=min(StartAddress+(BdySize−(StartAddress &−BdyMask)),StartAddress+vec_size).

Thereafter, the first operand (i.e., the designated vector register) isloaded, starting at indexed byte 0, from memory commencing at thestarting address and terminating at the ending address, STEP 680. Thisenables a variable number of bytes to be loaded from memory into avector without crossing a designated memory boundary. As indicatedabove, for instance, if the memory boundary is at 64 bytes, and thestarting address is at 58 bytes, then bytes 58-64 are loaded in thevector register. In one embodiment, the bytes are loaded in parallel.

One example of a vector register loaded, in accordance with eitherembodiment of the Vector Load to Block Boundary instruction, is depictedin FIG. 4C. As indicated, no data is loaded past the boundary designatedby the dashed vertical line in FIG. 4A. The locations past the boundaryare not accessible and no exception is taken. In one particularembodiment, the vector is loaded from left-to-right. However, in anotherembodiment, it can be loaded from right-to-left. In one embodiment, thedirection of the vectors, left-to-right or right-to-left, is provided atruntime. For instance, the instruction accesses a register, statuscontrol or other entity that indicates the direction of processing iseither left-to-right or right-to-left, as examples. In one embodiment,this direction control is not encoded as part of the instruction, butprovided to the instruction at runtime.

The Vector Load to Block Boundary instruction, in one example, onlyloads bytes of the vector register (the first operand) withcorresponding bytes of a second operand that are within a block of mainmemory (also referred to herein as main storage). The block of mainmemory is either specified in the instruction (e.g., the size isspecified in the instruction, as well as an address within the blockfrom which loading is to start) or dynamically determined by a type ofblock boundary (e.g., cache line or page) and one or morecharacteristics of the processor executing the instruction, such ascache line or page size. As used herein a block of main memory is anyblock of memory of a specified size. The specified size is also referredto as the boundary of the block, the boundary being the end of theblock.

One instruction used to find a termination character, such as a nullterminator, is a Vector Find Element Not Equal (VFBNEZ) instruction, anexample of which is depicted in FIG. 7. This instruction, in oneembodiment, is able to compare data of multiple vectors for inequality,as well as search a selected vector for a terminator, such as a null orzero element (e.g., the entire element is zero).

In one example, the Vector Find Element Not Equal instruction 700includes opcode fields 702 a (e.g., bits 0-7), 702 b (e.g., bits 40-47)indicating a Vector Find Element Not Equal operation; a first vectorregister field 704 (e.g., bits 8-11) used to designate a first vectorregister (V₁); a second vector register field 706 (e.g., bits 12-15)used to designate a second vector register (V₂); a third vector registerfield 708 (e.g., bits 16-19) used to designate a third vector register(V₃); a first mask field (M₅) 710 (e.g., bits 24-27); a second maskfield (M₄) 712 (e.g., bits 32-35); and an RXB field 714 (e.g., bits36-39). Each of the fields 704-714, in one example, is separate andindependent from the opcode field(s). Further, in one embodiment, theyare separate and independent from one another; however, in otherembodiments, more than one field may be combined. Further information onthe use of these fields is described below.

In one example, selected bits (e.g., the first two bits) of the opcodedesignated by opcode field 702 a specify the length and format of theinstruction. In this particular example, the selected bits indicate thatthe length is three halfwords, and the format is a vectorregister-and-register operation with an extended opcode field. Each ofthe vector (V) fields, along with its corresponding extension bitspecified by RXB, designates a vector register. In particular, forvector registers, the register containing the operand is specifiedusing, for instance, a four-bit field of the register field with theaddition of the register extension bit (RXB) as the most significantbit. For instance, if the four bit field is 0110 and the extension bitis 0, then the five bit field 00110 indicates register number 6.

The subscript number associated with a field of the instruction denotesthe operand to which the field applies. For instance, the subscriptnumber 1 associated with vector register V₁ denotes the first operand,and so forth. A register operand is one register in length, which is,for instance, 128 bits.

The M₄ field having, for instance, four bits, 0-3, specifies an elementsize control in, for instance, bits 1-3. The element size controlspecifies the size of the elements in the vector register operands. Inone example, the element size control can specify a byte, halfword(e.g., 2 bytes) or word (e.g., 4 bytes). For instance, a 0 indicates abyte; a 1 indicates a halfword; and a 2 indicates a word, a.k.a.,fullword. If a reserved value is specified, a specification exception isrecognized.

The M₅ field is, for instance, a four bit field, bits 0-3, including,for instance:

-   -   A zero search field (ZS, bit 2), which if one, each element of        the second operand is also compared to zero. (In a further        example, it is each element of the third operand or another        operand that is compared to zero.); and    -   A condition code set field (CC, bit 3), which if zero, the        condition code is not set and remains unchanged. If one, the        condition code is set as specified below, as an example:        -   0—If the zero search bit is set, comparison detected a zero            element in both operands in a lower index element than            unequal compares;        -   1—An element mismatch was detected and the element in V₂ is            less than the element in V₃;        -   2—An element mismatch was detected and the element in V₂ is            greater than the element in V₃; and        -   3—All elements compared equal, and if the zero search bit is            set, no zero elements were found in the second operand (or,            in another embodiment, other operands).

In execution of one embodiment of the Vector Find Element Not Equalinstruction, proceeding in one embodiment from left to right, theunsigned binary integer elements of the second operand (included in thevector register specified by V₂ and its extension bit) are compared withthe corresponding unsigned binary integer elements of the third operand(included in the vector register specified by the V₃ field plus itsextension bit). If two elements are not equal, a byte index of theleftmost non-equal element is placed in a specified byte (e.g., byte 7)of the first operand (designated in the register specified by V₁ and itsextension bit), and zeros are stored to all other bytes of the firstoperand.

In one example, the byte index of the element that is returned (e.g.,stored in the specified byte) is the index of the first byte of theleftmost element that is unequal. For instance, if the element size isbyte, then the index of the leftmost unequal element is returned (e.g.,if there are 16 elements, 0-15, and element 6 is unequal, then byteindex 6 is returned). Similarly, if the element size is halfword, andthere are 8 elements, 0-7, and either byte 6 or 7 of element three isunequal, then byte index 6 is returned. Likewise, if the element size isfullword and there are four elements, 0-3, and one of bytes 4-7 ofelement one is unequal, byte index 4 is returned.

If the condition code set bit in the M₅ field is set to, for instance,one, the condition code is set to indicate which operand was greater, ifany. That is, the binary integer equivalent of, for instance, acharacter in the second operand is compared to a binary integerequivalent of the unequal character in the third operand, and thecondition code is set based on this comparison. If elements were equal,then a byte index equal to the vector size (in number of bytes, e.g.,16) is placed in the specified byte (e.g., byte 7) of the first operandand zeros are placed in all other byte locations. If the condition codeset bit is one, a selected condition code (e.g., condition code 3) isset.

If the zero search bit is set in the M₅ field, each element in thesecond operand (or in other embodiments, the third operand or anotheroperand) is also compared for equality with zero (a.k.a., null,terminator, end of string, etc.). If a zero element is found in thesecond operand before any other element of the second operand is foundto be unequal, the byte index of the first byte of the element found tobe zero is stored in the specified byte (e.g., byte 7) of the firstoperand. Zeros are stored in all other bytes and a selected conditioncode (e.g., condition code zero) is set.

In one embodiment, the comparison of the elements is performed inparallel. For instance, if the vector registers being compared are 16bytes in length, then 16 bytes are compared in parallel. In otherembodiments, the units of data may be other than bytes, and the numberof compares in parallel corresponds to the unit size. Further, inanother embodiment, the direction of the vectors, left-to-right orright-to-left, is provided at runtime. For instance, the instructionaccesses a register, status control or other entity that indicates thedirection of processing as either left-to-right or right-to-left, asexamples. In one embodiment, this direction control is not encoded aspart of the instruction, but provided to the instruction at runtime.

In a further embodiment, the instruction does not include the RXB field.Instead, no extension is used or the extension is provided in anothermanner, such as from a control outside of the instruction, or providedas part of another field of the instruction.

Further details regarding one embodiment of processing the Vector FindElement Not Equal instruction are described with reference to FIG. 8. Inone example, a processor of the computing environment is performing thislogic.

Initially, a determination is made as to whether a search for null(a.k.a., zero element, end of string, terminator, etc.) is to beperformed, INQUIRY 800. If a search for null is to be performed, acomparison is made against null characters, i.e., for zero elements,STEP 802, and the result is output to nullidx 803. For instance, theindex of the left-most byte of the zero element is placed in nullidx.For example, if the element size is bytes and a zero element is found inbyte 5, the index of the byte in which the zero element is found (e.g.,5) is placed in nullidx. Similarly, if the element size is halfword, andthere are 8 elements, 0-7, and element three (i.e., bytes 6-7) is zero,then 6 (for byte index 6) is placed in nullidx. Likewise, if the elementsize is fullword and there are four elements, 0-3, and element one(i.e., bytes 4-7) is zero, then 4 (for byte index 4) is placed innullidx. If no null element is found, then, in one example, the size ofthe vector (e.g., in bytes; e.g., 16) is placed in nullidx.

Additionally, or if no null search is to be performed, a plurality ofcomparisons (e.g., 16) are performed in parallel comparing A to B basedon a compare operation, STEP 804. In one example, A is the contents ofthe second operand and B is the contents of the third operand, and thecompare operation is not equal.

A result of the compare is stored in a variable 806, referred to eitheras a left index, cmpidxl, or a right index, cmpidxr, depending onwhether the search is from the left or the right. For instance, if thecomparison is a not equal comparison, the search is left-to-right, andthe comparison results in one or more inequalities, the index associatedwith the first byte of the lowest unequal element is placed in cmpidxl.As one example, if the element size is bytes and there are 16 elementsin the vector (0-15) and an inequality is found in element 6, then 6 isstored in cmpidxl. Similarly, if the element size is halfwords, andthere are 8 elements in the vector (0-7), and an inequality is found inelement 3 (e.g., at byte 6 or 7), the index of the first byte of theelement (byte 6) is returned. Likewise, if the element size is fullwordand there are four elements (0-3), and an inequality is found in element1 (e.g., at byte 4-7), the index of the first byte of the element (byte4) is returned. If there are no unequal comparisons, then, in oneembodiment, cmpidxl or cmpidxr, depending on the direction of thecompare, is set equal to the size of the vector (e.g., in bytes; e.g.,16).

Thereafter, a determination is made as to whether the search is from theleft or right, INQUIRY 808. If the search is from the left, a variablecmpidx is set equal to cmpidxl, STEP 810; otherwise, cmpidx is set equalto cmpidxr, STEP 812.

Subsequent to setting cmpidx, a determination is made as to whether asearch was performed for null characters, INQUIRY 814. If there was nosearch for null characters, then a variable, idx, is set to, forinstance, the compare index, cmpidx, STEP 816. If null was searched,then idx is set to the minimum of the compare index or the null index,nullidx, STEP 818. This concludes processing.

An example of block logic for the processing of FIG. 8 is depicted inFIG. 9. In this example, there are two inputs, Vector B 900 and Vector A902. Both inputs are input to comparison logic 904, which performs thecomparisons (e.g., unequal) in parallel. Further, one input, Vector A,is also input to zero detection logic 906, which performs nullprocessing.

The output of the comparison logic, idxL or idxR 908, is input to resultdetermination logic 912, as well as the output of the zero detectionlogic, nullidx 910. The result determination logic also takes as inputthe following controls: right/left 914 indicating the direction of thesearch; zero detect 916 indicating whether null processing is to beperformed; and element size 918 providing the size of each element(e.g., byte, halfword, word); and produces a resulting index 920,resultidx, which is stored in an output vector 922 (e.g., in byte 7).

Further, the result determination logic includes condition codeprocessing 923, which optionally outputs a condition code 924.

Example pseudo-code for comparison logic 904 is as follows:

  idxL = 16; idxR = 16 For i = 0 to vector_length  If A[i]! = to B[i]THEN   idxL = i   Done For i = vector_length downto 0  If A[i]! = toB[i] THEN   idxR = i   done

As shown, variable idxL or idxR, depending on direction, is initializedto the size of the vector (e.g., in number of bytes; e.g., 16). Then,each element of Vector A is compared to a corresponding element ofVector B. In one example, the comparisons are byte comparisons, so acomparison is made for each of the 16 bytes (i). In this example, thecomparison operation is not equal, and if an inequality is found, theindex of the unequal byte is stored in idxL if searching from left, oridxR if searching from right.

Example pseudo-code for zero detection logic 906 is as follows:

  nullidx = 16 FOR j = 0 to vector_length IF A[j] == 0 THEN  nullidx = jx element_size  Done

As shown, each element (j) of the vector is tested to see if it is equalto zero. If an element is equal to zero, nullidx is set equal to theindex of that element times the element size. For instance, if theelement size if halfwords (2 bytes), and a null character is detected inelement 3, 3 is multiplied by 2, and nullidx is set to 6, whichrepresents byte 6. Similarly, if the element size is fullword (4 bytes),and a null character is detected in element 3, 3 is multiplied by 4, andnullidx is set to 12.

Likewise, example pseudo-code for result determination logic 912 asfollows:

  IF Left/Right = Left THEN  cmpidx = idxL ELSE  cmpidx = idxR IFzero_detect = ON THEN  resultidx = min (cmpidx, nullidx)  IF set_CC=ON&&nullidx <= cmpidx < 16 THEN   CC = 0 ELSE  resultidx = cmpidx IFelement_size = byte THEN element_size_mask = ^(|)11111^(|)b IFelement_size = 2byte THEN element_size_mask = ^(|)11110^(|)b IFelement_size = 4byte THEN element_size_mask = ^(|)11100^(|)b resultidx =resultidx & element_size_mask IF SetCC = ON THEN  IF resultidx == 16THEN   CC = 3  ELSE IF A[resultidx] < B[resultidx] THEN   CC = 1  ELSE  CC = 2 ELSE no updates to control code register

As shown, if the left/right control indicates left, then cmpidx is setequal to idxL; otherwise, cmpidx is set equal to idxR. Further, if thezero detect indicator is on, then resultidx is set equal to the minimumof cmpidx or nullidx; and if the condition code set control is on andcmpidx is greater than nullidx, the condition code is set to zero.Otherwise, if zero detect is not on, resultidx is set equal to cmpidx.

Further, if element size is equal to byte, then an element size mask isset to ^(ξ)11111^(ξ); if element size is equal to 2 bytes, the mask isset to ^(ξ)11110^(ξ), and if element size is equal to 4 bytes, the maskis set to ^(ξ)11100^(ξ).

Thereafter, resultidx is set equal to resultidx ANDed with element sizemask. For instance, if element size is halfword and byte 7 is resultidx,then resultidx=00111 AND 11110, providing 00110; so resultidx is setequal to 6 (i.e., 00110 binary), which is the first byte of the element.

Additionally, a condition code is optionally set. If the set conditioncode control of the instruction is set on, then a condition code isprovided; otherwise, no condition code is set. As examples, if thecontrol is set on, then if resultidx=16, the condition code is set to 3.Otherwise, if resultidx of A is less than resultidx of B, then thecondition code is set to 1; else, the condition code is set to 2.

For a 128 bit vector, the comparison logic only performs, for instance,16 byte compares, rather than, for instance, 256 compares. This providesfor scaling for larger vectors. Further, a left/right control may beprovided as a runtime value and not encoded within the instruction. Yetfurther, the value returned as the result is a byte position, ratherthan an element index. Further, 4 byte compares along with 1 byte and 2byte compares are supported.

In a further embodiment, the zero search is not a condition, butinstead, is performed when the Vector Find Element Not Equal instructionis executed. Based on or responsive to executing the instruction, thezero search is performed and the position (e.g., byte index) of the zeroelement is returned and/or the position (e.g., byte index) of the firstmismatched element. In one embodiment, the number of compares that areperformed, regardless of embodiment, for the Vector Find Element NotEqual instruction corresponds to the number of bytes of the vector. Forinstance, if the vector being searched or compared is 16 bytes, then atmost 16 compares are performed, e.g., in parallel. In a furtherembodiment, once a mismatch or zero element is found, the comparingceases.

One embodiment of a Load Count to Block Boundary (LCCB) instruction isdescribed with reference to FIG. 10. This instruction provides, forinstance, a count of the number of bytes of data from a specifiedaddress in memory to a specified memory boundary (e.g., it provides thenumber of bytes loaded in a vector register without crossing a specifiedboundary of the memory).

In one example, the Load Count to Block Boundary instruction 1000includes opcode fields 1002 a (e.g., bits 0-7), 1002 b (e.g., bits40-47) indicating a Load Count to Block Boundary operation; a registerfield 1004 (e.g., bits 8-11) used to designate a general purposeregister (R₁); an index field (X₂) 1006 (e.g., bits 12-15); a base field(B₂) 1008 (e.g., bits 16-19); a displacement field (D₂) 1010 (e.g., bits20-31); and a mask field (M₃) 1012 (e.g., bits 32-35). Each of thefields 1004-1012, in one example, is separate and independent from theopcode field(s). Further, in one embodiment, they are separate andindependent from one another; however, in other embodiments, more thanone field may be combined. Further information on the use of thesefields is described below.

In one example, selected bits (e.g., the first two bits) of the opcodedesignated by opcode field 1002 a specify the length and format of theinstruction. In this particular example, the length is three halfwords,and the format is a register-and-index-storage operation with anextended opcode field.

The subscript number associated with a field of the instruction denotesthe operand to which the field applies. For instance, the subscriptnumber 1 associated with R₁ denotes the first operand, and so forth. Theregister operand is one register in length, which is, for instance, 128bits.

In one example, in a register-and-index storage operation instruction,the contents of general registers designated by the X₂ and B₂ fields areadded to the contents of the D₂ field to form the second operandaddress. The displacement, D₂, for the Load Count to Block Boundaryinstruction is treated as a 12 bit unsigned integer, in one example. Thesecond operand address is used to indicate a location in main memory;however, it is not used to address data, in this embodiment.

The M₃ field, in one embodiment, specifies a code that is used to signalthe CPU as to the block boundary size to compute the number of possiblebytes to load without crossing a memory boundary. If a reserved value isspecified, a specification exception is recognized. Example codes andcorresponding values are as follows:

Code Boundary 0 64-Byte 1 128-Byte 2 256-Byte 3 512-Byte 4 1K-Byte 52K-Byte 6 4K-Byte

In a further example, the boundary size is not included in theinstruction, but instead, is dynamically determined by the processorexecuting the instruction. For instance, the M₃ field specifies the typeof boundary (e.g., cache line, page, etc.), and based on the type andone or more characteristics of the processor (e.g., cache line size forthe processor; page size for the processor; etc.), the processordetermines the boundary. As examples, based on the type, the processoruses a fixed size for the boundary (e.g., pre-defined fixed cache lineor page size for the processor), or based on the type, the processordetermines the boundary. For instance, if the type is a page boundary,the processor looks up the start address in a Translation Look-asideBuffer (TLB) and determines the page boundary therefrom. Other examplesalso exist. For example, the type may be provided by another field ofthe instruction or from a control outside of the instruction.

In execution of one embodiment of the Load Count to Block Boundaryinstruction, an unsigned binary integer (e.g., 64-bits) containing thenumber of bytes possible to load from the second operand locationwithout crossing a specified block boundary, capped at, for instance,the size of a vector register to be loaded (e.g., 16), is placed in thegeneral purpose register specified in the first operand. Resulting fromexecution of the instruction, an optional condition code is set, suchas, for example:

0 - Operand one is sixteen 1 - 2 - 3 - Operand one is less than sixteen

In the example instruction above, the starting address from which thecount is to begin is determined by the index register value (X₂)+a baseregister value (B₂)+a displacement (D₂); however, in other embodiments,it is provided by a register value; an instruction address+instructiontext specified offset; a register value+displacement; or a registervalue+index register value; as just some examples.

Further details of one embodiment of processing the Load Count to BlockBoundary instruction are described with reference to FIG. 11. In oneexample, a processor of the computing environment is performing thislogic.

In one embodiment, initially a boundary mask (BdyMask) is created, whichis used to determine closeness to the specified boundary, STEP 1100. Tocreate the mask, in one example, a 2's complement negation of a boundarysize (BdySize) 1102 is taken creating boundary mask 1104 (e.g.,BdyMask=0−BdySize). The boundary size is provided, in one example, bythe instruction (e.g., the M₃ field); or in another example, it isdetermined by the machine, as described herein.

Thereafter, a start address is computed, which indicates a location inmemory from which counting is to begin, STEP 1110. As examples, thestart address 1112 can be provided by a register value; an instructionaddress plus instruction text specified offset; a register value plusdisplacement; a register value plus index register value; or a registervalue plus index register value plus displacement. In the instructionprovided herein, the start address is provided by the X₂ field, B₂ fieldand D₂ field. That is, contents of the registers designated by X₂ and B₂are added to the displacement indicated by D₂ to provide the startingaddress. The above-indicated ways to compute a starting address are justexamples; other examples are also possible.

Next, an end address is computed indicating a location at which countingis to stop, STEP 1120. Input to this computation is, for instance,boundary size 1102, start address 1112, vector size (vec_size) 1114(e.g., in bytes; e.g., 16), and boundary mask 1104. The vector size isthe size of a vector register or other register (e.g., in bytes; e.g.,16). The register is, for instance, a register in which data may beloaded. In one example, end address 1122 is computed as follows:EndAddress=min(StartAddress+(BdySize−(StartAddress &−BdyMask)),StartAddress+vec_size).

Thereafter, the count is computed, STEP 1130. For instance,count=EndAddress 1122−StartAddress 1112. In a further example, count canbe computed from the start address and without using the end address. Inthis example, count=min(16, BdySize—(StartAddress AND BdyMask), where 16is the size of the vector register (or other register). In otherexamples, other vector sizes may be used.

In one embodiment, the Load to Count Block Boundary instruction is usedto determine how many bytes were loaded into a register, such as avector register. This count is used in the processing herein.

As indicated, in one embodiment, the registers that are compared arevector registers. There are, in one example of a vector facility, 32vector registers and other types of registers can map to a quadrant ofthe vector registers. For instance, as shown in FIG. 12, if there is aregister file 1200 that includes 32 vector registers 1202 and eachregister is 128 bits in length, then 16 floating point registers 1204which are 64 bits in length can overlay the vector registers. Thus, asan example, when floating point register 2 is modified, then vectorregister 2 is also modified. Other mappings for other types of registersare also possible.

Described in detail above is a technique for comparing sets ofterminated character data in parallel without causing unwarrantedexceptions. Typically, comparison of delimited strings is difficult todo in parallel because it is not known if one of the strings ends near apage boundary crossing where access across the page might cause anunwanted access exception. Previous techniques just copy one byte at atime or add checking to see if either string is near a boundary.

By using an instruction that loads data, in parallel, to a specifiedboundary and provides a way to determine the number of charactersloaded, and an instruction (which checks the data in parallel) to findthe index of the first delimiter or when two characters are not equal, atechnique is provided for comparing the sets of terminated characterdata (e.g., null terminated) with only one branch instruction. Further,fast parallel checking of string characters is provided, as well as theprevention of spurious exceptions.

Using one or more aspects of the above technique provides performanceimprovements, including reduced execution time.

Herein, memory, main memory, storage and main storage are usedinterchangeably, unless otherwise noted explicitly or by context.

Additional details relating to the vector facility, including examplesof other instructions, are provided as part of this Detailed Descriptionfurther below.

As will be appreciated by one skilled in the art, one or more aspects ofthe present invention may be embodied as a system, method or computerprogram product. Accordingly, one or more aspects of the presentinvention may take the form of an entirely hardware embodiment, anentirely software embodiment (including firmware, resident software,micro-code, etc.) or an embodiment combining software and hardwareaspects that may all generally be referred to herein as a “circuit,”“module” or “system”. Furthermore, one or more aspects of the presentinvention may take the form of a computer program product embodied inone or more computer readable medium(s) having computer readable programcode embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readablestorage medium. A computer readable storage medium may be, for example,but not limited to, an electronic, magnetic, optical, electromagnetic,infrared or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. More specific examples (a non-exhaustivelist) of the computer readable storage medium include the following: anelectrical connection having one or more wires, a portable computerdiskette, a hard disk, a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flashmemory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or anysuitable combination of the foregoing. In the context of this document,a computer readable storage medium may be any tangible medium that cancontain or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Referring now to FIG. 13, in one example, a computer program product1300 includes, for instance, one or more non-transitory computerreadable storage media 1302 to store computer readable program codemeans or logic 1304 thereon to provide and facilitate one or moreaspects of the present invention.

Program code embodied on a computer readable medium may be transmittedusing an appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for one or moreaspects of the present invention may be written in any combination ofone or more programming languages, including an object orientedprogramming language, such as Java, Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language, assembler or similar programming languages. Theprogram code may execute entirely on the user's computer, partly on theuser's computer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

One or more aspects of the present invention are described herein withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the invention. It will be understood that each block ofthe flowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of one or more aspects of the present invention. In thisregard, each block in the flowchart or block diagrams may represent amodule, segment, or portion of code, which comprises one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

In addition to the above, one or more aspects of the present inventionmay be provided, offered, deployed, managed, serviced, etc. by a serviceprovider who offers management of customer environments. For instance,the service provider can create, maintain, support, etc. computer codeand/or a computer infrastructure that performs one or more aspects ofthe present invention for one or more customers. In return, the serviceprovider may receive payment from the customer under a subscriptionand/or fee agreement, as examples. Additionally or alternatively, theservice provider may receive payment from the sale of advertisingcontent to one or more third parties.

In one aspect of the present invention, an application may be deployedfor performing one or more aspects of the present invention. As oneexample, the deploying of an application comprises providing computerinfrastructure operable to perform one or more aspects of the presentinvention.

As a further aspect of the present invention, a computing infrastructuremay be deployed comprising integrating computer readable code into acomputing system, in which the code in combination with the computingsystem is capable of performing one or more aspects of the presentinvention.

As yet a further aspect of the present invention, a process forintegrating computing infrastructure comprising integrating computerreadable code into a computer system may be provided. The computersystem comprises a computer readable medium, in which the computermedium comprises one or more aspects of the present invention. The codein combination with the computer system is capable of performing one ormore aspects of the present invention.

Although various embodiments are described above, these are onlyexamples. For example, computing environments of other architectures canincorporate and use one or more aspects of the present invention.Further, vectors of other sizes may be used, and changes to theinstruction may be made without departing from the spirit of the presentinvention. Additionally, other instructions may be used, such as, butnot limited to, a Vector Find Element Equal instruction to compare setsof terminated character data. Yet further, comparisons of other thannull terminated character data may also be performed using one or moreaspects of the present invention. Moreover, registers other than vectorregisters may be used, and/or the data may be other than character data,such as integer data or other types of data.

Further, other types of computing environments can benefit from one ormore aspects of the present invention. As an example, a data processingsystem suitable for storing and/or executing program code is usable thatincludes at least two processors coupled directly or indirectly tomemory elements through a system bus. The memory elements include, forinstance, local memory employed during actual execution of the programcode, bulk storage, and cache memory which provide temporary storage ofat least some program code in order to reduce the number of times codemust be retrieved from bulk storage during execution.

Input/Output or I/O devices (including, but not limited to, keyboards,displays, pointing devices, DASD, tape, CDs, DVDs, thumb drives andother memory media, etc.) can be coupled to the system either directlyor through intervening I/O controllers. Network adapters may also becoupled to the system to enable the data processing system to becomecoupled to other data processing systems or remote printers or storagedevices through intervening private or public networks. Modems, cablemodems, and Ethernet cards are just a few of the available types ofnetwork adapters.

Referring to FIG. 14, representative components of a Host Computersystem 5000 to implement one or more aspects of the present inventionare portrayed. The representative host computer 5000 comprises one ormore CPUs 5001 in communication with computer memory (i.e., centralstorage) 5002, as well as I/O interfaces to storage media devices 5011and networks 5010 for communicating with other computers or SANs and thelike. The CPU 5001 is compliant with an architecture having anarchitected instruction set and architected functionality. The CPU 5001may have dynamic address translation (DAT) 5003 for transforming programaddresses (virtual addresses) into real addresses of memory. A DATtypically includes a translation lookaside buffer (TLB) 5007 for cachingtranslations so that later accesses to the block of computer memory 5002do not require the delay of address translation. Typically, a cache 5009is employed between computer memory 5002 and the processor 5001. Thecache 5009 may be hierarchical having a large cache available to morethan one CPU and smaller, faster (lower level) caches between the largecache and each CPU. In some implementations, the lower level caches aresplit to provide separate low level caches for instruction fetching anddata accesses. In one embodiment, an instruction is fetched from memory5002 by an instruction fetch unit 5004 via a cache 5009. The instructionis decoded in an instruction decode unit 5006 and dispatched (with otherinstructions in some embodiments) to instruction execution unit or units5008. Typically several execution units 5008 are employed, for examplean arithmetic execution unit, a floating point execution unit and abranch instruction execution unit. The instruction is executed by theexecution unit, accessing operands from instruction specified registersor memory as needed. If an operand is to be accessed (loaded or stored)from memory 5002, a load/store unit 5005 typically handles the accessunder control of the instruction being executed. Instructions may beexecuted in hardware circuits or in internal microcode (firmware) or bya combination of both.

As noted, a computer system includes information in local (or main)storage, as well as addressing, protection, and reference and changerecording. Some aspects of addressing include the format of addresses,the concept of address spaces, the various types of addresses, and themanner in which one type of address is translated to another type ofaddress. Some of main storage includes permanently assigned storagelocations. Main storage provides the system with directly addressablefast-access storage of data. Both data and programs are to be loadedinto main storage (from input devices) before they can be processed.

Main storage may include one or more smaller, faster-access bufferstorages, sometimes called caches. A cache is typically physicallyassociated with a CPU or an I/O processor. The effects, except onperformance, of the physical construction and use of distinct storagemedia are generally not observable by the program.

Separate caches may be maintained for instructions and for dataoperands. Information within a cache is maintained in contiguous byteson an integral boundary called a cache block or cache line (or line, forshort). A model may provide an EXTRACT CACHE ATTRIBUTE instruction whichreturns the size of a cache line in bytes. A model may also providePREFETCH DATA and PREFETCH DATA RELATIVE LONG instructions which effectsthe prefetching of storage into the data or instruction cache or thereleasing of data from the cache.

Storage is viewed as a long horizontal string of bits. For mostoperations, accesses to storage proceed in a left-to-right sequence. Thestring of bits is subdivided into units of eight bits. An eight-bit unitis called a byte, which is the basic building block of all informationformats. Each byte location in storage is identified by a uniquenonnegative integer, which is the address of that byte location or,simply, the byte address. Adjacent byte locations have consecutiveaddresses, starting with 0 on the left and proceeding in a left-to-rightsequence. Addresses are unsigned binary integers and are 24, 31, or 64bits.

Information is transmitted between storage and a CPU or a channelsubsystem one byte, or a group of bytes, at a time. Unless otherwisespecified, in, for instance, the z/Architecture, a group of bytes instorage is addressed by the leftmost byte of the group. The number ofbytes in the group is either implied or explicitly specified by theoperation to be performed. When used in a CPU operation, a group ofbytes is called a field. Within each group of bytes, in, for instance,the z/Architecture, bits are numbered in a left-to-right sequence. Inthe z/Architecture, the leftmost bits are sometimes referred to as the“high-order” bits and the rightmost bits as the “low-order” bits. Bitnumbers are not storage addresses, however. Only bytes can be addressed.To operate on individual bits of a byte in storage, the entire byte isaccessed. The bits in a byte are numbered 0 through 7, from left toright (in, e.g., the z/Architecture). The bits in an address may benumbered 8-31 or 40-63 for 24-bit addresses, or 1-31 or 33-63 for 31-bitaddresses; they are numbered 0-63 for 64-bit addresses. Within any otherfixed-length format of multiple bytes, the bits making up the format areconsecutively numbered starting from 0. For purposes of error detection,and in preferably for correction, one or more check bits may betransmitted with each byte or with a group of bytes. Such check bits aregenerated automatically by the machine and cannot be directly controlledby the program. Storage capacities are expressed in number of bytes.When the length of a storage-operand field is implied by the operationcode of an instruction, the field is said to have a fixed length, whichcan be one, two, four, eight, or sixteen bytes. Larger fields may beimplied for some instructions. When the length of a storage-operandfield is not implied but is stated explicitly, the field is said to havea variable length. Variable-length operands can vary in length byincrements of one byte (or with some instructions, in multiples of twobytes or other multiples). When information is placed in storage, thecontents of only those byte locations are replaced that are included inthe designated field, even though the width of the physical path tostorage may be greater than the length of the field being stored.

Certain units of information are to be on an integral boundary instorage. A boundary is called integral for a unit of information whenits storage address is a multiple of the length of the unit in bytes.Special names are given to fields of 2, 4, 8, and 16 bytes on anintegral boundary. A halfword is a group of two consecutive bytes on atwo-byte boundary and is the basic building block of instructions. Aword is a group of four consecutive bytes on a four-byte boundary. Adoubleword is a group of eight consecutive bytes on an eight-byteboundary. A quadword is a group of 16 consecutive bytes on a 16-byteboundary. When storage addresses designate halfwords, words,doublewords, and quadwords, the binary representation of the addresscontains one, two, three, or four rightmost zero bits, respectively.Instructions are to be on two-byte integral boundaries. The storageoperands of most instructions do not have boundary-alignmentrequirements.

On devices that implement separate caches for instructions and dataoperands, a significant delay may be experienced if the program storesinto a cache line from which instructions are subsequently fetched,regardless of whether the store alters the instructions that aresubsequently fetched.

In one embodiment, the invention may be practiced by software (sometimesreferred to licensed internal code, firmware, micro-code, milli-code,pico-code and the like, any of which would be consistent with one ormore aspects the present invention). Referring to FIG. 14, softwareprogram code which embodies one or more aspects of the present inventionmay be accessed by processor 5001 of the host system 5000 from long-termstorage media devices 5011, such as a CD-ROM drive, tape drive or harddrive. The software program code may be embodied on any of a variety ofknown media for use with a data processing system, such as a diskette,hard drive, or CD-ROM. The code may be distributed on such media, or maybe distributed to users from computer memory 5002 or storage of onecomputer system over a network 5010 to other computer systems for use byusers of such other systems.

The software program code includes an operating system which controlsthe function and interaction of the various computer components and oneor more application programs. Program code is normally paged fromstorage media device 5011 to the relatively higher-speed computerstorage 5002 where it is available for processing by processor 5001. Thetechniques and methods for embodying software program code in memory, onphysical media, and/or distributing software code via networks are wellknown and will not be further discussed herein. Program code, whencreated and stored on a tangible medium (including but not limited toelectronic memory modules (RAM), flash memory, Compact Discs (CDs),DVDs, Magnetic Tape and the like is often referred to as a “computerprogram product”. The computer program product medium is typicallyreadable by a processing circuit preferably in a computer system forexecution by the processing circuit.

FIG. 15 illustrates a representative workstation or server hardwaresystem in which one or more aspects of the present invention may bepracticed. The system 5020 of FIG. 15 comprises a representative basecomputer system 5021, such as a personal computer, a workstation or aserver, including optional peripheral devices. The base computer system5021 includes one or more processors 5026 and a bus employed to connectand enable communication between the processor(s) 5026 and the othercomponents of the system 5021 in accordance with known techniques. Thebus connects the processor 5026 to memory 5025 and long-term storage5027 which can include a hard drive (including any of magnetic media,CD, DVD and Flash Memory for example) or a tape drive for example. Thesystem 5021 might also include a user interface adapter, which connectsthe microprocessor 5026 via the bus to one or more interface devices,such as a keyboard 5024, a mouse 5023, a printer/scanner 5030 and/orother interface devices, which can be any user interface device, such asa touch sensitive screen, digitized entry pad, etc. The bus alsoconnects a display device 5022, such as an LCD screen or monitor, to themicroprocessor 5026 via a display adapter.

The system 5021 may communicate with other computers or networks ofcomputers by way of a network adapter capable of communicating 5028 witha network 5029. Example network adapters are communications channels,token ring, Ethernet or modems. Alternatively, the system 5021 maycommunicate using a wireless interface, such as a CDPD (cellular digitalpacket data) card. The system 5021 may be associated with such othercomputers in a Local Area Network (LAN) or a Wide Area Network (WAN), orthe system 5021 can be a client in a client/server arrangement withanother computer, etc. All of these configurations, as well as theappropriate communications hardware and software, are known in the art.

FIG. 16 illustrates a data processing network 5040 in which one or moreaspects of the present invention may be practiced. The data processingnetwork 5040 may include a plurality of individual networks, such as awireless network and a wired network, each of which may include aplurality of individual workstations 5041, 5042, 5043, 5044.Additionally, as those skilled in the art will appreciate, one or moreLANs may be included, where a LAN may comprise a plurality ofintelligent workstations coupled to a host processor.

Still referring to FIG. 16, the networks may also include mainframecomputers or servers, such as a gateway computer (client server 5046) orapplication server (remote server 5048 which may access a datarepository and may also be accessed directly from a workstation 5045). Agateway computer 5046 serves as a point of entry into each individualnetwork. A gateway is needed when connecting one networking protocol toanother. The gateway 5046 may be preferably coupled to another network(the Internet 5047 for example) by means of a communications link. Thegateway 5046 may also be directly coupled to one or more workstations5041, 5042, 5043, 5044 using a communications link. The gateway computermay be implemented utilizing an IBM eServer™ System z server availablefrom International Business Machines Corporation.

Referring concurrently to FIG. 15 and FIG. 16, software programming codewhich may embody one or more aspects of the present invention may beaccessed by the processor 5026 of the system 5020 from long-term storagemedia 5027, such as a CD-ROM drive or hard drive. The softwareprogramming code may be embodied on any of a variety of known media foruse with a data processing system, such as a diskette, hard drive, orCD-ROM. The code may be distributed on such media, or may be distributedto users 5050, 5051 from the memory or storage of one computer systemover a network to other computer systems for use by users of such othersystems.

Alternatively, the programming code may be embodied in the memory 5025,and accessed by the processor 5026 using the processor bus. Suchprogramming code includes an operating system which controls thefunction and interaction of the various computer components and one ormore application programs 5032. Program code is normally paged fromstorage media 5027 to high-speed memory 5025 where it is available forprocessing by the processor 5026. The techniques and methods forembodying software programming code in memory, on physical media, and/ordistributing software code via networks are well known and will not befurther discussed herein. Program code, when created and stored on atangible medium (including but not limited to electronic memory modules(RAM), flash memory, Compact Discs (CDs), DVDs, Magnetic Tape and thelike is often referred to as a “computer program product”. The computerprogram product medium is typically readable by a processing circuitpreferably in a computer system for execution by the processing circuit.

The cache that is most readily available to the processor (normallyfaster and smaller than other caches of the processor) is the lowest (L1or level one) cache and main store (main memory) is the highest levelcache (L3 if there are 3 levels). The lowest level cache is oftendivided into an instruction cache (I-Cache) holding machine instructionsto be executed and a data cache (D-Cache) holding data operands.

Referring to FIG. 17, an exemplary processor embodiment is depicted forprocessor 5026. Typically one or more levels of cache 5053 are employedto buffer memory blocks in order to improve processor performance. Thecache 5053 is a high speed buffer holding cache lines of memory datathat are likely to be used. Typical cache lines are 64, 128 or 256 bytesof memory data. Separate caches are often employed for cachinginstructions than for caching data. Cache coherence (synchronization ofcopies of lines in memory and the caches) is often provided by various“snoop” algorithms well known in the art. Main memory storage 5025 of aprocessor system is often referred to as a cache. In a processor systemhaving 4 levels of cache 5053, main storage 5025 is sometimes referredto as the level 5 (L5) cache since it is typically faster and only holdsa portion of the non-volatile storage (DASD, tape etc) that is availableto a computer system. Main storage 5025 “caches” pages of data paged inand out of the main storage 5025 by the operating system.

A program counter (instruction counter) 5061 keeps track of the addressof the current instruction to be executed. A program counter in az/Architecture processor is 64 bits and can be truncated to 31 or 24bits to support prior addressing limits. A program counter is typicallyembodied in a PSW (program status word) of a computer such that itpersists during context switching. Thus, a program in progress, having aprogram counter value, may be interrupted by, for example, the operatingsystem (context switch from the program environment to the operatingsystem environment). The PSW of the program maintains the programcounter value while the program is not active, and the program counter(in the PSW) of the operating system is used while the operating systemis executing. Typically, the program counter is incremented by an amountequal to the number of bytes of the current instruction. RISC (ReducedInstruction Set Computing) instructions are typically fixed length whileCISC (Complex Instruction Set Computing) instructions are typicallyvariable length. Instructions of the IBM z/Architecture are CISCinstructions having a length of 2, 4 or 6 bytes. The Program counter5061 is modified by either a context switch operation or a branch takenoperation of a branch instruction for example. In a context switchoperation, the current program counter value is saved in the programstatus word along with other state information about the program beingexecuted (such as condition codes), and a new program counter value isloaded pointing to an instruction of a new program module to beexecuted. A branch taken operation is performed in order to permit theprogram to make decisions or loop within the program by loading theresult of the branch instruction into the program counter 5061.

Typically an instruction fetch unit 5055 is employed to fetchinstructions on behalf of the processor 5026. The fetch unit eitherfetches “next sequential instructions”, target instructions of branchtaken instructions, or first instructions of a program following acontext switch. Modern Instruction fetch units often employ prefetchtechniques to speculatively prefetch instructions based on thelikelihood that the prefetched instructions might be used. For example,a fetch unit may fetch 16 bytes of instruction that includes the nextsequential instruction and additional bytes of further sequentialinstructions.

The fetched instructions are then executed by the processor 5026. In anembodiment, the fetched instruction(s) are passed to a dispatch unit5056 of the fetch unit. The dispatch unit decodes the instruction(s) andforwards information about the decoded instruction(s) to appropriateunits 5057, 5058, 5060. An execution unit 5057 will typically receiveinformation about decoded arithmetic instructions from the instructionfetch unit 5055 and will perform arithmetic operations on operandsaccording to the opcode of the instruction. Operands are provided to theexecution unit 5057 preferably either from memory 5025, architectedregisters 5059 or from an immediate field of the instruction beingexecuted. Results of the execution, when stored, are stored either inmemory 5025, registers 5059 or in other machine hardware (such ascontrol registers, PSW registers and the like).

A processor 5026 typically has one or more units 5057, 5058, 5060 forexecuting the function of the instruction. Referring to FIG. 18A, anexecution unit 5057 may communicate with architected general registers5059, a decode/dispatch unit 5056, a load store unit 5060, and other5065 processor units by way of interfacing logic 5071. An execution unit5057 may employ several register circuits 5067, 5068, 5069 to holdinformation that the arithmetic logic unit (ALU) 5066 will operate on.The ALU performs arithmetic operations such as add, subtract, multiplyand divide as well as logical function such as and, or and exclusive-or(XOR), rotate and shift. Preferably the ALU supports specializedoperations that are design dependent. Other circuits may provide otherarchitected facilities 5072 including condition codes and recoverysupport logic for example. Typically the result of an ALU operation isheld in an output register circuit 5070 which can forward the result toa variety of other processing functions. There are many arrangements ofprocessor units, the present description is only intended to provide arepresentative understanding of one embodiment.

An ADD instruction for example would be executed in an execution unit5057 having arithmetic and logical functionality while a floating pointinstruction for example would be executed in a floating point executionhaving specialized floating point capability. Preferably, an executionunit operates on operands identified by an instruction by performing anopcode defined function on the operands. For example, an ADD instructionmay be executed by an execution unit 5057 on operands found in tworegisters 5059 identified by register fields of the instruction.

The execution unit 5057 performs the arithmetic addition on two operandsand stores the result in a third operand where the third operand may bea third register or one of the two source registers. The execution unitpreferably utilizes an Arithmetic Logic Unit (ALU) 5066 that is capableof performing a variety of logical functions such as Shift, Rotate, And,Or and XOR as well as a variety of algebraic functions including any ofadd, subtract, multiply, divide. Some ALUs 5066 are designed for scalaroperations and some for floating point. Data may be Big Endian (wherethe least significant byte is at the highest byte address) or LittleEndian (where the least significant byte is at the lowest byte address)depending on architecture. The IBM z/Architecture is Big Endian. Signedfields may be sign and magnitude, 1's complement or 2's complementdepending on architecture. A 2's complement number is advantageous inthat the ALU does not need to design a subtract capability since eithera negative value or a positive value in 2's complement requires only anaddition within the ALU. Numbers are commonly described in shorthand,where a 12 bit field defines an address of a 4,096 byte block and iscommonly described as a 4 Kbyte (Kilo-byte) block, for example.

Referring to FIG. 18B, branch instruction information for executing abranch instruction is typically sent to a branch unit 5058 which oftenemploys a branch prediction algorithm such as a branch history table5082 to predict the outcome of the branch before other conditionaloperations are complete. The target of the current branch instructionwill be fetched and speculatively executed before the conditionaloperations are complete. When the conditional operations are completedthe speculatively executed branch instructions are either completed ordiscarded based on the conditions of the conditional operation and thespeculated outcome. A typical branch instruction may test conditioncodes and branch to a target address if the condition codes meet thebranch requirement of the branch instruction, a target address may becalculated based on several numbers including ones found in registerfields or an immediate field of the instruction for example. The branchunit 5058 may employ an ALU 5074 having a plurality of input registercircuits 5075, 5076, 5077 and an output register circuit 5080. Thebranch unit 5058 may communicate with general registers 5059, decodedispatch unit 5056 or other circuits 5073, for example.

The execution of a group of instructions can be interrupted for avariety of reasons including a context switch initiated by an operatingsystem, a program exception or error causing a context switch, an I/Ointerruption signal causing a context switch or multi-threading activityof a plurality of programs (in a multi-threaded environment), forexample. Preferably a context switch action saves state informationabout a currently executing program and then loads state informationabout another program being invoked. State information may be saved inhardware registers or in memory for example. State informationpreferably comprises a program counter value pointing to a nextinstruction to be executed, condition codes, memory translationinformation and architected register content. A context switch activitycan be exercised by hardware circuits, application programs, operatingsystem programs or firmware code (microcode, pico-code or licensedinternal code (LIC)) alone or in combination.

A processor accesses operands according to instruction defined methods.The instruction may provide an immediate operand using the value of aportion of the instruction, may provide one or more register fieldsexplicitly pointing to either general purpose registers or specialpurpose registers (floating point registers for example). Theinstruction may utilize implied registers identified by an opcode fieldas operands. The instruction may utilize memory locations for operands.A memory location of an operand may be provided by a register, animmediate field, or a combination of registers and immediate field asexemplified by the z/Architecture long displacement facility wherein theinstruction defines a base register, an index register and an immediatefield (displacement field) that are added together to provide theaddress of the operand in memory for example. Location herein typicallyimplies a location in main memory (main storage) unless otherwiseindicated.

Referring to FIG. 18C, a processor accesses storage using a load/storeunit 5060. The load/store unit 5060 may perform a load operation byobtaining the address of the target operand in memory 5053 and loadingthe operand in a register 5059 or another memory 5053 location, or mayperform a store operation by obtaining the address of the target operandin memory 5053 and storing data obtained from a register 5059 or anothermemory 5053 location in the target operand location in memory 5053. Theload/store unit 5060 may be speculative and may access memory in asequence that is out-of-order relative to instruction sequence, howeverthe load/store unit 5060 is to maintain the appearance to programs thatinstructions were executed in order. A load/store unit 5060 maycommunicate with general registers 5059, decode/dispatch unit 5056,cache/memory interface 5053 or other elements 5083 and comprises variousregister circuits, ALUs 5085 and control logic 5090 to calculate storageaddresses and to provide pipeline sequencing to keep operationsin-order. Some operations may be out of order but the load/store unitprovides functionality to make the out of order operations to appear tothe program as having been performed in order, as is well known in theart.

Preferably addresses that an application program “sees” are oftenreferred to as virtual addresses. Virtual addresses are sometimesreferred to as “logical addresses” and “effective addresses”. Thesevirtual addresses are virtual in that they are redirected to physicalmemory location by one of a variety of dynamic address translation (DAT)technologies including, but not limited to, simply prefixing a virtualaddress with an offset value, translating the virtual address via one ormore translation tables, the translation tables preferably comprising atleast a segment table and a page table alone or in combination,preferably, the segment table having an entry pointing to the pagetable. In the z/Architecture, a hierarchy of translation is providedincluding a region first table, a region second table, a region thirdtable, a segment table and an optional page table. The performance ofthe address translation is often improved by utilizing a translationlookaside buffer (TLB) which comprises entries mapping a virtual addressto an associated physical memory location. The entries are created whenthe DAT translates a virtual address using the translation tables.Subsequent use of the virtual address can then utilize the entry of thefast TLB rather than the slow sequential translation table accesses. TLBcontent may be managed by a variety of replacement algorithms includingLRU (Least Recently used).

In the case where the processor is a processor of a multi-processorsystem, each processor has responsibility to keep shared resources, suchas I/O, caches, TLBs and memory, interlocked for coherency. Typically,“snoop” technologies will be utilized in maintaining cache coherency. Ina snoop environment, each cache line may be marked as being in any oneof a shared state, an exclusive state, a changed state, an invalid stateand the like in order to facilitate sharing.

I/O units 5054 (FIG. 17) provide the processor with means for attachingto peripheral devices including tape, disc, printers, displays, andnetworks for example. I/O units are often presented to the computerprogram by software drivers. In mainframes, such as the System z fromIBM®, channel adapters and open system adapters are I/O units of themainframe that provide the communications between the operating systemand peripheral devices.

Further, other types of computing environments can benefit from one ormore aspects of the present invention. As an example, an environment mayinclude an emulator (e.g., software or other emulation mechanisms), inwhich a particular architecture (including, for instance, instructionexecution, architected functions, such as address translation, andarchitected registers) or a subset thereof is emulated (e.g., on anative computer system having a processor and memory). In such anenvironment, one or more emulation functions of the emulator canimplement one or more aspects of the present invention, even though acomputer executing the emulator may have a different architecture thanthe capabilities being emulated. As one example, in emulation mode, thespecific instruction or operation being emulated is decoded, and anappropriate emulation function is built to implement the individualinstruction or operation.

In an emulation environment, a host computer includes, for instance, amemory to store instructions and data; an instruction fetch unit tofetch instructions from memory and to optionally, provide localbuffering for the fetched instruction; an instruction decode unit toreceive the fetched instructions and to determine the type ofinstructions that have been fetched; and an instruction execution unitto execute the instructions. Execution may include loading data into aregister from memory; storing data back to memory from a register; orperforming some type of arithmetic or logical operation, as determinedby the decode unit. In one example, each unit is implemented insoftware. For instance, the operations being performed by the units areimplemented as one or more subroutines within emulator software.

More particularly, in a mainframe, architected machine instructions areused by programmers, usually today “C” programmers, often by way of acompiler application. These instructions stored in the storage mediummay be executed natively in a z/Architecture IBM® Server, oralternatively in machines executing other architectures. They can beemulated in the existing and in future IBM® mainframe servers and onother machines of IBM® (e.g., Power Systems servers and System x®Servers). They can be executed in machines running Linux on a widevariety of machines using hardware manufactured by IBM®, Intel®, AMD™,and others. Besides execution on that hardware under a z/Architecture,Linux can be used as well as machines which use emulation by Hercules,UMX, or FSI (Fundamental Software, Inc), where generally execution is inan emulation mode. In emulation mode, emulation software is executed bya native processor to emulate the architecture of an emulated processor.

The native processor typically executes emulation software comprisingeither firmware or a native operating system to perform emulation of theemulated processor. The emulation software is responsible for fetchingand executing instructions of the emulated processor architecture. Theemulation software maintains an emulated program counter to keep trackof instruction boundaries. The emulation software may fetch one or moreemulated machine instructions at a time and convert the one or moreemulated machine instructions to a corresponding group of native machineinstructions for execution by the native processor. These convertedinstructions may be cached such that a faster conversion can beaccomplished. Notwithstanding, the emulation software is to maintain thearchitecture rules of the emulated processor architecture so as toassure operating systems and applications written for the emulatedprocessor operate correctly. Furthermore, the emulation software is toprovide resources identified by the emulated processor architectureincluding, but not limited to, control registers, general purposeregisters, floating point registers, dynamic address translationfunction including segment tables and page tables for example, interruptmechanisms, context switch mechanisms, Time of Day (TOD) clocks andarchitected interfaces to I/O subsystems such that an operating systemor an application program designed to run on the emulated processor, canbe run on the native processor having the emulation software.

A specific instruction being emulated is decoded, and a subroutine iscalled to perform the function of the individual instruction. Anemulation software function emulating a function of an emulatedprocessor is implemented, for example, in a “C” subroutine or driver, orsome other method of providing a driver for the specific hardware aswill be within the skill of those in the art after understanding thedescription of the preferred embodiment. Various software and hardwareemulation patents including, but not limited to U.S. Letters Pat. No.5,551,013, entitled “Multiprocessor for Hardware Emulation”, byBeausoleil et al.; and U.S. Letters Pat. No. 6,009,261, entitled“Preprocessing of Stored Target Routines for Emulating IncompatibleInstructions on a Target Processor”, by Scalzi et al; and U.S. LettersPat. No. 5,574,873, entitled “Decoding Guest Instruction to DirectlyAccess Emulation Routines that Emulate the Guest Instructions”, byDavidian et al; and U.S. Letters Pat. No. 6,308,255, entitled“Symmetrical Multiprocessing Bus and Chipset Used for CoprocessorSupport Allowing Non-Native Code to Run in a System”, by Gorishek et al;and U.S. Letters Pat. No. 6,463,582, entitled “Dynamic Optimizing ObjectCode Translator for Architecture Emulation and Dynamic Optimizing ObjectCode Translation Method”, by Lethin et al; and U.S. Letters Pat. No.5,790,825, entitled “Method for Emulating Guest Instructions on a HostComputer Through Dynamic Recompilation of Host Instructions”, by EricTraut, each of which is hereby incorporated herein by reference in itsentirety; and many others, illustrate a variety of known ways to achieveemulation of an instruction format architected for a different machinefor a target machine available to those skilled in the art.

In FIG. 19, an example of an emulated host computer system 5092 isprovided that emulates a host computer system 5000′ of a hostarchitecture. In the emulated host computer system 5092, the hostprocessor (CPU) 5091 is an emulated host processor (or virtual hostprocessor) and comprises an emulation processor 5093 having a differentnative instruction set architecture than that of the processor 5091 ofthe host computer 5000′. The emulated host computer system 5092 hasmemory 5094 accessible to the emulation processor 5093. In the exampleembodiment, the memory 5094 is partitioned into a host computer memory5096 portion and an emulation routines 5097 portion. The host computermemory 5096 is available to programs of the emulated host computer 5092according to host computer architecture. The emulation processor 5093executes native instructions of an architected instruction set of anarchitecture other than that of the emulated processor 5091, the nativeinstructions obtained from emulation routines memory 5097, and mayaccess a host instruction for execution from a program in host computermemory 5096 by employing one or more instruction(s) obtained in asequence & access/decode routine which may decode the hostinstruction(s) accessed to determine a native instruction executionroutine for emulating the function of the host instruction accessed.Other facilities that are defined for the host computer system 5000′architecture may be emulated by architected facilities routines,including such facilities as general purpose registers, controlregisters, dynamic address translation and I/O subsystem support andprocessor cache, for example. The emulation routines may also takeadvantage of functions available in the emulation processor 5093 (suchas general registers and dynamic translation of virtual addresses) toimprove performance of the emulation routines. Special hardware andoff-load engines may also be provided to assist the processor 5093 inemulating the function of the host computer 5000′.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising”, when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of one or more aspects of the present inventionhas been presented for purposes of illustration and description, but isnot intended to be exhaustive or limited to the invention in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art without departing from the scope and spiritof the invention. The embodiment was chosen and described in order tobest explain the principles of the invention and the practicalapplication, and to enable others of ordinary skill in the art tounderstand the invention for various embodiments with variousmodifications as are suited to the particular use contemplated.

Chapter 23. Vector String Instructions

Vector String Facility

Instructions

Unless otherwise specified all operands are vector-register operands. A“V” in the assembler syntax designates a vector operand.

Op- Name Mnemonic Characteristics code Page VECTOR FIND ANY EQUAL VFAEVRR-b C* VF ¤⁹ SP Dv E782 23-1 VECTOR FIND ELEMENT EQUAL VFEE VRR-b C*VF ¤⁹ SP Dv E780 23-2 VECTOR FIND ELEMENT NOT EQUAL VFENE VRR-b C* VF ¤⁹SP Dv E781 23-3 VECTOR STRING RANGE COMPARE VSTRC VRR-d C* VF ¤⁹ SP DvE78A 23-4

Vector Find any Equal

Proceeding from left to right, every unsigned binary integer element ofthe second operand is compared for equality with each unsigned binaryinteger element of the third operand and optionally zero if the ZeroSearch flag is set in the M₅ field.

If the Result Type (RT) flag in the M₅ field is zero, then for eachelement in the second operand that matches any element in the thirdoperand, or optionally zero, the bit positions of the correspondingelement in the first operand are set to ones, otherwise they are set tozero.

If the Result Type (RT) flag in the M₅ field is one, then the byte indexof the leftmost element in the second operand that matches an element inthe third operand or zero is stored in byte seven of the first operand.

Each instruction has an Extended Mnemonic section which describerecommended extended mnemonics and their corresponding machine assemblersyntax.

Programming Note: For all instructions that optionally set the conditioncode, performance may be degraded if the condition code is set.

If the result Type (RT) flag in the M₅ field is one and no bytes arefound to be equal, or zero if the zero search flag is set, an indexequal to the number of bytes in the vector is stored in byte seven ofthe first operand.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₅ field has the following format:

The bits of the M₅ field are defined as follows:

-   -   Result Type (RT): If zero, each resulting element is a mask of        all range comparisons on that element. If one, a byte index is        stored into byte seven of the first operand and zeros are stored        in all other elements.    -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code is not set        and remains unchanged. If one, the condition code is set as        specified in the following section.

Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M₄ field contains a value from 3-15.

2. Bit 0 of the M₅ field are not zero.

Resulting Condition Code:

If the CC flag is zero, the code remains unchanged.

If the CC flag is one, the code is set as follows:

-   0 If the ZS-bit is set, there were no matches in a lower indexed    element than zero in the second operand.-   1 Some elements of the second operand match at least one element in    the third operand-   2 All elements of the second operand matched at least one element in    the third operand No elements in the second operand match any    elements in the third operand    Program Exceptions:    1 Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VFAEB V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0, M₅ VFAEH V₁, V₂, V₃, M₅ VFAEV₁, V₂, V₃, 1, M₅ VFAEF V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 2, M₅ VFAEBS V₁,V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0, (M₅ | X′1′) VFAEHS V₁, V₂, V₃, M₅ VFAEV₁, V₂, V₃, 1, (M₅ | X′1′) VFAEFS V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 2, (M₅| X′1′) VFAEZB V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0, (M₅ | X′2′) VFAEZH V₁,V₂, V₃, M₅ VFAE V₁, V₂, V₃, 1, (M₅ | X′2′) VFAEZF V₁, V₂, V₃, M₅ VFAEV₁, V₂, V₃, 2, (M₅ | X′2′) VFAEZBS V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0,(M₅ | X′3′) VFAEZHS V₁, V₂, V₃, M₅ VFAE V₁, V2, V3, 1, (M₅ | X′3′)VFAEZFS V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 2, (M₅ | X′3′)Vector Find Element Equal

Proceeding from left to right, the unsigned binary integer elements ofthe second operand are compared with the corresponding unsigned binaryinteger elements of the third operand. If two elements are equal, thebyte index of the first byte of the leftmost equal element is placed inbyte seven of the first operand. Zeros are stored in the remaining bytesof the first operand. If no bytes are found to be equal, or zero if thezero compare is set, then an index equal to the number of bytes in thevector is stored in byte seven of the first operand. Zeros are stored inthe remaining bytes.

If the Zero Search (ZS) bit is set in the M₅ field, then each element inthe second operand is also compared for equality with zero. If a zeroelement is found in the second operand before any other elements of thesecond and third operands are found to be equal, the byte index of thefirst byte of the element found to be zero is stored in byte seven thefirst operand and zeros are stored in all other byte locations. If theCondition Code Set (CC) flag is one, then the condition code is set tozero.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₅ field has the following format:

The bits of the M₅ field are defined as follows:

-   -   Reserved: Bits 0-1 are reserved and must be zero. Otherwise, a        specification exception is recognized.    -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code remains        unchanged. If one, the condition code is set as specified in the        following section.        Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M₄ field contains a value from 3-15.

2. Bits 0-1 of the M₅ field are not zero.

Resulting Condition Code:

If bit 3 of the M₅ field is set to one, the code is set as follows:

0 If the zero compare bit is set, comparison detected a zero element inthe second operand in an element with a smaller index than any equalcomparisons. 1 Comparison detected a match between the second and thirdoperands in some element. If the zero compare bit is set, this matchoccurred in an element with an index less than or equal to the zerocomparing element. 2 — 3 No elements compared equal.

If bit 3 of the M₅ field is zero, the code remains unchanged.

Program Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VFEEB V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 0, M₅ VFEEH V₁, V₂, V₃, M₅ VFEEV₁, V₂, V₃, 1, M₅ VFEEF V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 0, (M₅ | X′1′)VFEEHS V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 1, (M₅ | X′1′) VFEEFS V₁, V₂, V₃,M₅ VFEE V₁, V₂, V₃, 2, (M₅ | X′1′) VFEEZB V₁, V₂, V₃, M₅ VFEE V₁, V₂,V₃, 0, (M₅ | X′2′) VFEEZH V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 1, (M₅ | X′2′)VFEEZF V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 2, (M₅ | X′2′) VFEEZBS V₁, V₂,V₃, M₅ VFEE V₁, V₂, V₃, 0, (M₅ | X′3′) VFEEZHS V₁, V₂, V₃, M₅ VFEE V₁,V₂, V₃, 1, (M₅ | X′3′) VFEEZFS V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 2, (M₅ |X′3′)Programming Notes:1. A byte index is always stored into the first operand for any elementsize. For example, if the element size was set to halfword and the2^(nd) indexed halfword compared equal, then a byte index of 4 would bestored.2. The third operand should not contain elements with a value of zero.If the third operand does contain a zero and it matches with a zeroelement in the second operand before any other equal comparisons,condition code one is set regardless of the zero compare bit setting.Vector Find Element not Equal

Proceeding from left to right, the unsigned binary integer elements ofthe second operand are compared with the corresponding unsigned binaryinteger elements of the third operand. If two elements are not equal,the byte index of the left-most non-equal element is placed in byteseven of the first operand and zeros are stored to all other bytes. Ifthe Condition Code Set (CC) bit in the M₅ field is set to one, thecondition code is set to indicate which operand was greater. If allelements were equal, then abyte index equal to the vector size is placedin byte seven of the first operand and zeros are placed in all otherbyte locations. If the CC bit is one, condition code three is set.

If the zero search (ZS) bit is set in the M₅ field, each element in thesecond operand is also compared for equality with zero. If a zeroelement is found in the second operand before any other element of thesecond operand are found to be unequal, the byte index of the first byteof the element fount to be zero is stored in byte seven of the firstoperand. Zeros are stored in all other bytes and condition code 0 isset.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₅ field has the following format:

The bits of the M₅ field are defined as follows:

-   -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code is not set        and remains unchanged.

If one, the condition code is set as specified in the following section.

Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M₄ field contains a value from 3-15.

2. Bits 0-1 of the M₅ field are not zero.

Resulting Condition Code:

If bit 3 of the M₅ field is set to one, the code is set as follows:

0 If the zero, compare bit is set, comparison detected a zero element inboth operands in a lower indexed element than any unequal compares 1 Anelement mismatch was detected and the element in VR2 is less than theelement in VR3 2 An element mismatch was detected and the element in VR2is greater than the element in VR3 3 All elements compared equa1, and ifthe zero compare bit is set, no zero elements were found in the secondoperand.

If bit 3 of the M₅ field is zero, the code remains unchanged.

Program Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VFENEB V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 0, M₅ VFENEH V₁, V₂, V₃, M₅VFENE V₁, V₂, V₃, 1, M₅ VFENEF V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 2, M₅VFENEBS V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 0, (M₅ | X′1′) VFENEHS V₁, V₂,V₃, M₅ VFENE V₁, V₂, V₃, 1, (M₅ | X′1′) VFENEFS V₁, V₂, V₃, M₅ VFENE V₁,V₂, V₃, 2, (M₅ | X′1′) VFENEZB V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 0, (M₅ |X′2′) VFENEZH V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 1, (M₅ | X′2′) VFENEZFV₁, V₂, V₃, M₅ VFENE V₁, V2, V3, 2, (M₅ | X′2′) VFENEZBS V₁, V₂, V₃, M₅VFENE V₁, V₂, V₃, 0, (M₅ | X′3′) VFENEZHS V₁, V₂, V₃, M₅ VFENE V₁, V₂,V₃, 1, (M₅ | X′3′) VFENEZFS V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 2, (M₅ |X′3′)Vector String Range Compare

Proceeding from left to right, the unsigned binary integer elements inthe second operand are compared to ranges of values defined by even-oddpairs of elements in the third and fourth operands. The combined withcontrol values from the fourth operand define the range of comparisonsto be performed. If an element matches any of the ranges specified bythe third and fourth operands, it is considered to be a match.

If the Result Type (RT) flag in the M6 field is zero, the bit positionsof the element in the first operand corresponding to the element beingcompared in the second operand are set to one if the element matches anyof the ranges, otherwise they are set to zero.

If the Result Type (RT) flag in the M₆ field is set to one, the byteindex of the first element in the second operand that matches any of theranges specified by the third and fourth operands or a zero comparison,if the ZS flag is set to one, is placed in byte seven of the firstoperand and zeros are stored in the remaining bytes. If no elementsmatch, then an index equal to the number of bytes in a vector is placedin byte seven of the first operand and zeros are stored in the remainingbytes.

The Zero Search (ZS) flag in the M₆ field, if set to one, will add acomparison to zero of the second operand elements to the ranges providedby the third and fourth operands. If a zero comparison in a lowerindexed element than any other true comparison, then the condition codeis set to zero.

The operands contain elements of the size specified by the Element Sizecontrol in the M₅ field.

The fourth operand elements have the following format:

If ES equals 0:

If ES equals 1:

If ES equals 2:

The bits in the fourth operand elements are defined as follows:

-   -   Equal (EQ): When one a comparison for equality is made.    -   Greater Than (GT): When one a greater than comparison is        performed.    -   Less Than (LT): When one a less than comparison is performed.    -   All other bits are reserved and should be zero to ensure future        compatibility.

The control bits may be used in any combination. If none of the bits areset, the comparison will always produce a false result. If all of thebits are set, the comparison will always produce a true result.

The M₅ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₆ field has the following format:

The bits of the M₆ field are defined as follows:

-   -   Invert Result (IN): If zero, the comparison proceeds with the        pair of values in the control vector. If one, the result of the        pairs of the comparisons in the ranges are inverted.    -   Result Type (RT): If zero, each resulting element is a mask of        all range comparisons on that element. If one, an index is        stored into byte seven of the first operand. Zeroes are stored        in the remaining bytes.    -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code is not set        and remains unchanged. If one, the condition code is set as        specified in the following section.        Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M₄ field contains a value from 3-15.

Resulting Condition Code:

0 If ZS = 1 and a zero is found in a lower indexed element than anycompare 1 Comparison found 2 — 3 No comparison foundProgram Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VSTRCB V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 0, M₆ VSTRCH V₁, V₂, V₃,V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 1, M₆ VSTRCF V₁, V₂, V₃, V₄, M₆ VSTRC V₁,V₂, V₃, V₄, 2, M₆ VSTRCBS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 0,(M₆ | X′1′) VSTRCHS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 1, (M₆ |X′1′) VSTRCFS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 2, (M₆ | X′1′)VSTRCZB V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 0, (M₆ | X′2′) VSTRCZHV₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 1, (M₆ | X′2′) VSTRCZF V₁, V₂,V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 2, (M₆ | X′2′) VSTRCZBS V₁, V₂, V₃, V₄,M₆ VSTRC V₁, V₂, V₃, V₄, 0, (M₆ | X′3′) VSTRCZHS V₁, V₂, V₃, V₄, M₆VSTRC V₁, V₂, V₃, V₄, 1, (M₆ | X′3′) VSTRCZFS V₁, V₂, V₃, V₄, M₆ VSTRCV₁, V₂, V₃, V₄, 2, (M₆ | X′3′)

Figure 23-1.

ES = 1, ZS = 0 VR1(a) Results with RT = 0 VR1(b) Results with RT = 1Load Count to Block Boundary

A 32-bit unsigned binary integer containing the number of bytes possibleto load from the second operand location without crossing a specifiedblock boundary, capped at sixteen is placed in the first operand.

The displacement is treated as a 12-bit unsigned integer.

The second operand address is not used to address data.

The M₃ field specifies a code that is used to signal the CPU as to theblock boundary size to compute the number of possible bytes loaded. If areserved value is specified then a specification exception isrecognized.

Code Boundary

0 64-Byte

1 128-Byte

2 256-Byte

3 512-Byte

4 1K-Byte

5 2K-Byte

6 4K-Byte

7-15 Reserved

Resulting Condition Code:

0 Operand one is sixteen 1 — 2 — 3 Operand one less than sixteenResulting Condition Code:Program Exceptions:

-   -   Operation if the vector-extension facility is not installed    -   Specification

Programming Note: It is expected that LOAD COUNT TO BLOCK BOUNDARY willbe used in conjunction with VECTOR LOAD TO BLOCK BOUNDARY to determinethe number of bytes that were loaded.

Vector Load GR from VR Element

The element of the third operand of size specified by the ES value inthe M₄ field and indexed by the second operand address is placed in thefirst operand location. The third operand is a vector register. Thefirst operand is a general register. If the index specified by thesecond operand address is greater than the highest numbered element inthe third operand, of the specified element size, the data in the firstoperand is unpredictable.

If the vector register element is smaller than a doubleword, the elementis right aligned in the 64-bit general register and zeros fill theremaining bits.

The second operand address is not used to address data; instead therightmost 12 bits of the address are used to specify the index of anelement within the second operand.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3—Doubleword

4-15—Reserved unchanged.

Resulting Condition Code: The code is unchanged.

Program Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:        VLGVB R₁,V₃,D₂(B₂) VLGV R1,V3,D2(B₂),0

VLGVB R1, V3, D2(B2) VLGV R1, V3, D2(B2), 0 VLGVH R1, V3, D2(B2) VLGVR1, V3, D2(B2), 1 VLGVF R1, V3, D2(B2) VLGV R1, V3, D2(B2), 2 VLGVG R1,V3, D2(B2) VLGV R1, V3, D2(B2), 3Vector Load to Block Boundary

The first operand is loaded starting at the zero indexed byte elementwith bytes from the second operand. If a boundary condition isencountered, the rest of the first operand is unpredictable. Accessexceptions are not recognized on bytes not loaded.

The displacement for VLBB is treated as a 12-bit unsigned integer.

The M₃ field specifies a code that is used to signal the CPU as to theblock boundary size to load to. If a reserved value is specified, aspecification exception is recognized.

Code Boundary

0 64-Byte

1 128-Byte

2 256-Byte

3 512-Byte

4 1K-Byte

5 2K-Byte

6 4K-Byte

7-15 Reserved

Resulting Condition Code: The code remains unchanged.

Program Exceptions:

-   -   Access (fetch, operand 2)    -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved Block Boundary Code)    -   Transaction Constraint        Programming Notes:        1. In certain circumstances data may be loaded past the block        boundary. However, this will only occur if there are no access        exceptions on that data.        Vector Store

The 128-bit value in the first operand is stored to the storage locationspecified by the second operand. The displacement for VST is treated asa 12-bit unsigned integer.

Resulting Condition Code: The code remains unchanged.

Program Exceptions:

-   -   Access (store, operand 2)    -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Transaction Constraint        Vector Store with Length

Proceeding from left to right, bytes from the first operand are storedat the second operand location. The general register specified thirdoperand contains a 32-bit unsigned integer containing a value thatrepresents the highest indexed byte to store. If the third operandcontains a value greater than or equal to the highest byte index of thevector, all bytes of the first operand are stored.

Access exceptions are only recognized on bytes stored.

The displacement for VECTOR STORE WITH LENGTH is treated as a 12-bitunsigned integer.

Resulting Condition Code: The condition code remains unchanged.

Program Exceptions:

-   -   Access (store, operand 2)    -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Transaction Constraint        RXB Description

All vector instructions have a field in bits 36-40 of the instructionlabeled as RXB. This field contains the most significant bits for all ofthe vector register designated operands. Bits for register designationsnot specified by the instruction are reserved and should be set to zero;otherwise, the program may not operate compatibly in the future. Themost significant bit is concatenated to the left of the four-bitregister designation to create the five-bit vector register designation.

The bits are defined as follows:

0. Most significant bit for the vector register designation in bits 8-11of the instruction.

1. Most significant bit for the vector register designation in bits12-15 of the instruction.

2. Most significant bit for the vector register designation in bits16-19 of the instruction.

3. Most significant bit for the vector register designation in bits32-35 of the instruction.

Vector Enablement Control

The vector registers and instructions may only be used if both thevector enablement control (bit 46) and the AFP-register-control (bit 45)in control register zero are set to one. If the vector facility isinstalled and a vector instruction is executed without the enablementbits set, a data exception with DXC FE hex is recognized. If the vectorfacility is not installed, an operation exception is recognized.

What is claimed is:
 1. A method of comparing characters of a pluralityof sets of data, the method comprising: loading from memory to a firstregister, a variable amount of first data that is within a firstspecified block of memory, the first data being at least a portion of afirst set of data to be compared, and the loading comprising loadingfrom memory the first data into the first register without crossing afirst specified boundary of the memory from which the data is loaded,the first specified boundary being based on a pre-defined size of thefirst specified block of memory, and wherein the loading starts at afirst starting address within the first specified block of memory andterminates at a first ending address within the first specified block ofmemory, the first ending address determined based on the pre-definedsize such that the first specified boundary is not crossed; loading frommemory to a second register, second data that is within a secondspecified block of memory, the second data being at least a portion of asecond set of data to be compared; computing a first count of an amountof the first data loaded in the first register and a second count of anamount of second data loaded in the second register; determining, by aprocessor, a value, the determining including performing at least one ofA) or B): A) comparing the first data loaded in the first register withthe second data loaded in the second register searching for an unequalcharacter; and B) searching at least one of the first register and thesecond register for a termination character; and based on at least oneof the comparing and the searching, setting the value to one of alocation of the unequal character, a location of the terminationcharacter, or a pre-specified value based on not finding an unequalcharacter or a termination character; checking whether the first set ofdata or the second set of data has additional data to be compared, thechecking using at least one of the first count and the second count; andbased on the checking indicating additional data is to be compared,comparing the additional data of the first set of data or the second setof data with data of the other set of the first set of data or thesecond set of data.
 2. The method of claim 1, wherein the additionaldata is located within one of: a third specified block of memory, or thefirst specified block of memory or the second specified block of memorybased on whether the additional data is of the first set of data or thesecond set of data, and wherein the data compared to the additional datais located within one of: a fourth specified block of memory, or thefirst specified block of memory or the second specified block of memorybased on whether the data is of the first set of data or the second setof data.
 3. The method of claim 1, wherein the checking whether thefirst set of data or the second set of data has additional data to becompared comprises: setting a minimum value to a smaller of the firstcount and the second count; incrementing the value by the minimum value;and comparing the minimum value with the value to determine whetheradditional data is to be compared.
 4. The method of claim 3, whereinadditional data is to be compared based on the minimum value being lessthan the value.
 5. The method of claim 1, wherein the computing thefirst count comprises using a start address within the first specifiedblock of memory and a boundary of the first specified block of memory tocompute the first count.
 6. The method of claim 1, wherein the firstdata comprises a plurality of first units of data and the second datacomprises a plurality of second units of data, and wherein at least oneof the first plurality of units of data and the second plurality ofunits of data are loaded in parallel, and wherein the comparing thefirst data and the second data is performed in parallel.
 7. The methodof claim 1, wherein at least one of the loading the first data and theloading the second data is performed by a Vector Load to Block Boundaryinstruction, and the block of memory is one of: specified by the VectorLoad to Block Boundary instruction, or dynamically determined by aprocessor executing the Vector Load to Block Boundary instruction. 8.The method of claim 1, wherein at least one of computing the first countand computing the second count comprises using a Load Count to BlockBoundary instruction.
 9. The method of claim 1, wherein the determiningcomprises using a Vector Find Element Not Equal instruction, wherein theVector Find Element Not Equal instruction performs the comparing, thesearching and the setting.
 10. The method of claim 1, wherein no morethan one branch instruction is used in the comparing characters of theplurality of sets of data.
 11. The method of claim 1, wherein the methodfurther comprises obtaining computer code, the computer code including aVector Load to Block Boundary instruction to perform the loading of thefirst data and the loading of the second data, a Load Count to BlockBoundary instruction to compute the first count and the second count,and a Vector Find Element Not Equal instruction to determine the value.12. The method of claim 1, further comprising determining the firstending address, the determining comprising: first ending address=minimumof (first starting address+(boundary size−(first starting address ANDNOT boundary mask)), first starting address+first register size),wherein the boundary size is the pre-defined size, boundary mask isequal to 0−boundary size, and register size is a specified length of thefirst register.